可以在钢轨、尖轨、心轨顶面处站立。
参考答案:错
Kelly cooked dinner her parents while they were cleaning the yard.
A. with
B. for
C. to
斜坡型牙槽嵴的舌杆应安放在()
A.牙槽嵴的非倒凹区
B.与黏膜轻轻接触
C.离开黏膜0.5mm
D.位于牙龈与舌系带之间不影响舌运动
E.牙槽嵴的倒凹区内