A bed and a computer_____in my bedroom. [ ]
A. are
B. is
C. has
D. have
答案：A
低压水泵电机寿命往往超过25000小时，一般认为低压水泵电机平均寿命为（）年。
A.5
B.10
C.15
D.20
菌根圈 mycorrhizosphere
