问题补充：
We can’t fix this machine well. Can you show us ?
A. how to do
B. what to do it
C. how to do it
D. where to do
答案：
A. how to do
B. what to do it
(答案→)C. how to do it
D. where to do
解析：句意：我们不能修理好这台机器，你能给我们展示一下如何去修理它吗？what to do 做什么；how to do sth 如何做某事；where to do sth 到哪里去做某事。根据句意，故选C。
