阀门检验（）未使用的应100%复检。
A、3个月
B、半年
C、一年
D、一年半
参考答案：B
已知集合A={1，2}，B={x|x2-2ax+b=0}，若B≠∅，且A∪B=A，求实数a，b的值．
Knowing the result of the exam,he went home and lay in bed, ____. [ ]
A. upset
B. was upset
C. felt upset
D. and upsets
