问题补充：
He wondered his son was getting along with the experiment.
A. when
B. what
C. how
D. which
答案：
A. when
B. what
(答案→)C. how
D. which
解析：主要测试宾语从句。从具体的题干考虑可知动词wonder需要宾语从句，另外结合以前所学知识可知对固定短语get along well with sth中副词well的提问需要引导词how。至此答案一目了然。译文：他在想儿子的实验进展的如何了。
