There ____________ a shelf in the study.[ ]
A. am
B. is
C. are
答案：B
—What were you doing when the rock star arrived?
— .[ ]
A. I was doing my homework
B. I am doing my homework
C. I do my homework
D. I did my homework
有机物CH3CH(C2H5)CH(CH3)2的名称是 __________ 。
