A.杠杆
B.轮轴
C.斜面
D.定滑轮
答案:C
Tom is _____ honest man and now he is living in Belgium, _____ European country.
A.an, an
B.a, an
C.an, a
D.an, the
查海遗址,是一处距今约7—8千年的()时代早期原始部落遗址。
A.旧石期
B.新石期
C.青铜期
D.铁器