液化气罐上的压力表，应定期（），压力表的精度不低于（）级，表盘上应标有（）的警戒红线。
参考答案：校验；1.5；最高工作压力
炎症期拔牙或阻生牙拔除，可在术前后给予__________预防感染。
John slept late quite often and his frequent lateness for work led to .
A．him to be fired
B．fire him
C．him having fired
D．his being fired
