英语翻译16`how can he be ____stupid>?a much b thatc such d enoug

英语翻译
16`how can he be ____stupid>?
a much
b that
c such
d enough
17`before the final examination,some students have shown __ _____of tension.they even have trouble in sleeping.
a anxiety
b marks
c signs
remarks
18`five-yearold children are too young to go to school,___?
a are they
b aren't they
c were they
d have they
19`when lily came home at 5 p.m.yesterday,her mother ____dinner in the kitchen.
a cooked
b was cooking
c cooks
d hascooked
20`hardly____on stage____the audience started cheering.
a he had come/than
b he had come/when
c had he come/when
d had he come/than
给选择就可以了谢谢!