How many ears do you have?[ ]
A. 2
B. 1
C. 3
答案：A
My father is so kind thak he is to all of my friends.[ ]
A. friend
B. friends
C. friendly
D. friendship
分馏塔顶压力升高，分馏塔底液面（）
A、上升
B、不变
C、下降
