The energy source on Voyager 2 is not a nuclear reactor, in which atoms are actively broken apart; rather a kind of nuclear battery that uses natural radioactive decay to produce power.
apart; rather
apart, but rather
apart, but rather that of
apart, but that of
apart; it is that of
not x, but rather y,中间用逗号,这是固定搭配。
我把它当成了用分号链接的排比句,然而它并不是一个排比,还要注意not but 的句型,其实but后是完整句子,只不过省略了前面可省略的The energy source on Voyager 2 is
that of 指代不明
The correct version of this sentence focuses on a contrast by using the construction //not x, but rather y//.
not x, but rather y,中间用逗号,这是固定搭配。其他选项,that of 指代不明确