乳尖牙萌出（）
A.新生儿期
B.婴儿期
C.幼儿期
D.混合牙列阶段
E.年轻恒牙列阶段
参考答案：C
—What’s that noise? Is the water still running?
—Oh, my god! I ________to turn it off after I brushed my teeth．
A．was forgetting
B．forgot
C．had forgotten
D．am forgetting
WK—4型挖掘机推压机构保险闸的优缺点是什么？
