I went to the park .[ ]
A. now
B. tomorrow
C. soon
D. yesterday
答案：D
磁性无杆气缸的缸内既无气缸杆，又无活塞，所以才称为“无杆气缸”。
Life preservers must be marked with the（）.
A.stowage space assigned
B.vessel's name
C.vessel's home port
D.maximum weight allowed
