diff --git a/po/R-zh_CN.po b/po/R-zh_CN.po
index ec3b630c3c..0b437f3efb 100644
--- a/po/R-zh_CN.po
+++ b/po/R-zh_CN.po
@@ -87,87 +87,95 @@ msgid "; filled with NA"
 msgstr ""
 
 msgid "A column may not be called .SD. That has special meaning."
-msgstr ""
+msgstr "无法将列命名为 .SD，因为 .SD 为特殊符号。"
 
 msgid "class must be length 1"
-msgstr ""
+msgstr "class 的长度必须为 1"
 
 msgid "between has been passed an argument x of type logical"
-msgstr ""
+msgstr "传入 between 的参数 x 为逻辑（logical）型"
 
 msgid ""
 "'between' function the 'x' argument is a POSIX class while 'lower' was not, "
 "coercion to POSIX failed with:"
 msgstr ""
+"'between' 中的 'x' 参数为 POSIX 类，而 'lower' 并不是，"
+"将 'lower' 自动转换成 POSIX 失败："
 
 msgid ""
 "'between' function the 'x' argument is a POSIX class while 'upper' was not, "
 "coercion to POSIX failed with:"
 msgstr ""
+"'between' 中的 'x' 参数为 POSIX 类，而 'upper' 并不是，"
+"将 'upper' 自动转换成 POSIX 失败："
 
 msgid ""
 "'between' lower= and upper= are both POSIXct but have different tzone "
 "attributes:"
 msgstr ""
+"'between' 中的 lower= 和 upper= 均为 POSIXct 类型但却有不同的时区"
+"属性（tzone）："
 
 msgid ". Please align their time zones."
-msgstr ""
+msgstr "。请确保二者的时区一致。"
 
 msgid ""
 "'between' arguments are all POSIXct but have mismatched tzone attributes:"
 msgstr ""
+"'between' 的参数均为 POSIXct 类型但时区属性（tzone）不匹配："
 
 msgid ". The UTC times will be compared."
-msgstr ""
+msgstr "。将采用 UTC 时间进行比较。"
 
 msgid "trying to use integer64 class when 'bit64' package is not installed"
-msgstr ""
+msgstr "试图使用 intger64 类型但 'bit64' 包尚未安装"
 
 msgid ""
 "Not yet implemented NAbounds=TRUE for this non-numeric and non-character type"
 msgstr ""
+"对这种非数值（numeric）和非字符（character）的类型，尚未实现 NAbounds=TRUE 的功能"
 
 msgid "Some lower>upper for this non-numeric and non-character type"
-msgstr ""
+msgstr "对于该非数值（numeric）和非字符（character）类型的输入，存在一部分下界（lower）> 上界（upper）的情况"
 
 msgid "RHS has length()"
-msgstr ""
+msgstr "右手侧（RHS）的长度为"
 
 msgid "; expecting length 2."
-msgstr ""
+msgstr "；其长度应为 2。"
 
 msgid "c"
 msgstr ""
 
 msgid "Perhaps you meant %s?"
-msgstr ""
+msgstr "或许你想用的是 %s？"
 
 msgid "The first element should be the lower bound(s);"
-msgstr ""
+msgstr "第一个元素应为下界；"
 
 msgid "the second element should be the upper bound(s)."
-msgstr ""
+msgstr "第二个元素应为上界。"
 
 msgid "x."
 msgstr ""
 
 msgid "is type"
-msgstr ""
+msgstr "的类型为"
 
 msgid "which is not supported by data.table join"
-msgstr ""
+msgstr "，该类型无法用于 data.table 的联接"
 
 msgid "i."
 msgstr ""
 
 msgid "Attempting roll join on factor column when joining x."
-msgstr ""
+msgstr "试图滚动联接（roll join）因子类型（factor）的列，这发生于将 x."
 
 msgid "to i."
-msgstr ""
+msgstr "与 i."
 
 msgid ". Only integer, double or character columns may be roll joined."
-msgstr ""
+msgstr "联接时。但只有整数（integer）、双精度（double）或字符（character）类型的列可以使用滚动联接（roll join）。"
 
 msgid "Incompatible join types: x."
 msgstr ""
diff --git a/po/zh_CN.po b/po/zh_CN.po
index 146c133e9d..0d5ecee7b6 100644
--- a/po/zh_CN.po
+++ b/po/zh_CN.po
@@ -172,25 +172,28 @@ msgid ""
 "a logical subset, simply wrap with which(), and take the which() outside the "
 "loop if possible for efficiency."
 msgstr ""
+"i 为 '%s' 类型。i 必须为整（integer）型，或数值（numeric）型（将被自动转换成整型并发出警告）。如果 i 为"
+"一个用于筛选的逻辑（logical）向量，请直接将它传给 which()，且如果可能的话将 which() 放置于"
+"循环之外以保持高效。"
 
 #: assign.c:331
 #, c-format
 msgid "i[%d] is %d which is out of range [1,nrow=%d]."
-msgstr ""
+msgstr "i[%d] 为 %d 且超出了范围 [1,nrow=%d]。"
 
 #: assign.c:334
 #, c-format
 msgid "Assigning to %d row subset of %d rows\n"
-msgstr ""
+msgstr "正在为 %d 行（总数为 %d 行）进行赋值\n"
 
 #: assign.c:342
 #, c-format
 msgid "Added %d new column%s initialized with all-NA\n"
-msgstr ""
+msgstr "添加了 %d 个新列 %s 并全部初始化为 NA\n"
 
 #: assign.c:347
 msgid "length(LHS)==0; no columns to delete or assign RHS to."
-msgstr ""
+msgstr "左手侧长度为0（length(LHS)==0）；没有列可供删除或赋值给右手侧（RHS）。"
 
 #: assign.c:361
 msgid ""
@@ -198,12 +201,17 @@ msgid ""
 "Please use a data.table for that. data.table's are over-allocated and don't "
 "shallow copy."
 msgstr ""
+"数据框（data.frame）的 set() 是用于修改现有列，而非添加新列。"
+"请使用 data.table 来添加新列。data.table 的操作是超额分配的（over-allocated）并且不"
+"进行浅拷贝（shallow copy）。"
 
 #: assign.c:372
 msgid ""
 "Coerced j from numeric to integer. Please pass integer for efficiency; e.g., "
 "2L rather than 2"
 msgstr ""
+"将 j 从数值（numeric）型自动转换为整（integer）型。为了保持高效请直接传入整型，如"
+"2L 而非 2"
 
 #: assign.c:375
 #, c-format
@@ -211,21 +219,25 @@ msgid ""
 "j is type '%s'. Must be integer, character, or numeric is coerced with "
 "warning."
 msgstr ""
+"j 为 '%s' 型。j 必须为整（integer）型、字符（character）型，或数值（numeric）型（将被自动转换成整型"
+"并发出警告）。"
 
 #: assign.c:377
 msgid ""
 "Can't assign to the same column twice in the same query (duplicates "
 "detected)."
 msgstr ""
+"在一次查询中无法对同一列赋值两次（检测出
+重复项）。"
 
 #: assign.c:378
 msgid "newcolnames is supplied but isn't a character vector"
-msgstr ""
+msgstr "指定了 newcolnames 但其并非一字符串向量"
 
 #: assign.c:380
 #, c-format
 msgid "RHS_list_of_columns == %s\n"
-msgstr ""
+msgstr "RHS_list_of_columns == %s\n"
 
 #: assign.c:385
 #, c-format
@@ -233,6 +245,8 @@ msgid ""
 "RHS_list_of_columns revised to true because RHS list has 1 item which is "
 "NULL, or whose length %d is either 1 or targetlen (%d). Please unwrap RHS.\n"
 msgstr ""
+"RHS_list_of_columns 改为真（True），因为右手侧列表（RHS list）有一子项"
+"为空值（NULL）或长度 %d 为 1 或 targetlen（%d）。请拆开右手侧。\n"
 
 #: assign.c:390
 #, c-format
@@ -241,17 +255,21 @@ msgid ""
 "table or data.frame since they are lists too). To delete multiple columns "
 "use NULL instead. To add multiple empty list columns, use list(list())."
 msgstr ""
+"试图将 %d 列赋值为空列表（可能为空数据、"
+"表（table）或数据框（data.frame），因后两者也是列表的一种）。删除多个列时"
+"请使用空值（NULL）。添加多个空列表列（list columns）时，请使用 list(list())。"
 
 #: assign.c:395
 #, c-format
 msgid "Recycling single RHS list item across %d columns. Please unwrap RHS.\n"
-msgstr ""
+msgstr "回收重用（Recycling）单个右手侧（RHS）列表子项于 %d 列。请拆开右手侧。\n"
 
 #: assign.c:397
 #, c-format
 msgid ""
 "Supplied %d columns to be assigned %d items. Please see NEWS for v1.12.2."
 msgstr ""
+"试图将 %2$d 项赋值给 %1$d 列。请阅读 v1.12.2 的更新信息（NEWS）。"
 
 #: assign.c:405
 #, c-format
@@ -260,6 +278,9 @@ msgid ""
 "set() on a data.frame is for changing existing columns, not adding new ones. "
 "Please use a data.table for that."
 msgstr ""
+"j 中的列编号里第 %d 项是 %d，超出了有效范围 [1,ncol=%d]。"
+"数据框（data.frame）的 set() 是用于修改现有列，而非添加新列。"
+"请使用 data.table 来添加新列。"
 
 #: assign.c:406
 #, c-format
@@ -267,10 +288,12 @@ msgid ""
 "Item %d of column numbers in j is %d which is outside range [1,ncol=%d]. Use "
 "column names instead in j to add new columns."
 msgstr ""
+"j 中的列编号里第 %d 项是 %d，超出了有效范围 [1,ncol=%d]。请在 j 中使用"
+"列名来添加新列。"
 
 #: assign.c:411
 msgid "When deleting columns, i should not be provided"
-msgstr ""
+msgstr "当删除列时，不应指定 i"
 
 #: assign.c:417
 #, c-format
@@ -282,22 +305,29 @@ msgid ""
 "full length RHS vector such as vector('list',nrow(DT)); i.e., 'plonk' in the "
 "new column."
 msgstr ""
+"对已有列 '%s' 的赋值其右手侧（RHS）长度为零但并非空值（NULL）。如果"
+"想要删除列请使用空值（NULL）。否则，右手侧必须"
+"长度 > 0，如 NA_integer_。如果想将该列类型修改为"
+"空列表列（list column），正如所有修改列类型的操作一样，请在右手侧提供一个"
+"与该列原数据等长的向量，如 vector('list',nrow(DT))，即，用新数据替换（plonk）重新生成"
+"该列。"
 
 #: assign.c:422
 #, c-format
 msgid ""
 "Internal error in assign.c: length(newcolnames)=%d, length(names)=%d, coln=%d"
 msgstr ""
+"assign.c 内部错误：length(newcolnames)=%d, length(names)=%d, coln=%d"
 
 #: assign.c:424
 #, c-format
 msgid "Column '%s' does not exist to remove"
-msgstr ""
+msgstr "要删除的列 '%s' 不存在"
 
 #: assign.c:430
 #, c-format
 msgid "%d column matrix RHS of := will be treated as one vector"
-msgstr ""
+msgstr "':=' 右手侧（RHS）%d 列矩阵将被视为一维向量"
 
 #: assign.c:434
 #, c-format
@@ -305,6 +335,8 @@ msgid ""
 "Can't assign to column '%s' (type 'factor') a value of type '%s' (not "
 "character, factor, integer or numeric)"
 msgstr ""
+"无法给因子（factor）类型列 '%s' 赋类型为 '%s' 的值（不是"
+"字符（character）、因子（factor）、整数（integer）或数值（numeric）类中的一种）"
 
 #: assign.c:439
 #, c-format
@@ -313,6 +345,9 @@ msgid ""
 "'recycle' the RHS please use rep() to make this intent clear to readers of "
 "your code."
 msgstr ""
+"试图将 %d 项赋值给 %d 项（列 '%s'）。如果想"
+"'回收重用'（'recycle'）右手侧，请使用 rep() 以将该意图清晰地表述给阅读"
+"代码的人。"
 
 #: assign.c:449
 msgid ""
@@ -321,6 +356,10 @@ msgid ""
 "or setalloccol() on it first (to pre-allocate space for new columns) before "
 "assigning by reference to it."
 msgstr ""
+"该 data.table 为从磁盘中载入（如使用 readRDS()/"
+"load()）或手动创建（如使用 structure()）。请首先对其运行 setDT() "
+"或 setalloccol() （以为新列预分配内存空间），然后再进行"
+"引用赋值（assigning by reference）操作。"
 
 #: assign.c:450
 #, c-format