单项选择。
Here is a picture you. [ ]
A. of
B. with
C. to
D. at
答案：A
—How long did the trip from Rugao to Nanjing ______ you?
— About three hours.
A．cost
B．take
C．spend
D．pay
一个容器内贮有1mol氢气和1mol氦气，若两种气体各自对器壁产生的压强分别为P1和P2，则两者的大小关系是（）。
A．P1＞P2
B．P1＞P2
C．P1=P2
D．不确定
