手提式1211灭火器技术性能表有（）种型号。
A.3
B.4
C.5
D.6
参考答案：C
The problem in today's parenting environment is ________ many believe it is their job to solve all their
children's problems. [ ]
A. who
B. that
C. which
D. what
按紧急停机开关使空压机立即停机，按启动按钮空压机重新启动。（）
