1.— Why didn’t you come to Mike’s birthday party yesterday?
— Well, I ____, but I forgot it.
A. should B. must C. should have D. must have
选C。should have的后面省略了come。should have come表示“本应该而实际上没有”。
2.A computer is so useful a machine ________ we can use everywhere.
A. that B. which C. as D. what
选C。本题考查句子结构和关系代词的选用。首先表示认清句子结构，use后面应该接一个及物动词，先行词应该充当宾语，而前面出现so useful不能用that与which来修饰，可以排除。另外，what 不能引导定语从句。
