英语题帮帮忙！

c
let只有let sb do something
所以a,b should be crossed out.
next,the complete structure of the sentence:when will they leave him to go home?意思是（直译）
他们什么时候离开他不去管他，而让他回家呢？
leave sb to do something 意思是，放任某人做某事。

C

c

b

句子还原就是
he will be allowed to go home When.
they will let him to go when
所以应该选b