减速器有哪些优点?
参考答案:
优点:结构紧凑,效率较高,传递运动准确可靠,使用维护简单,并可能成批生产,故在机器中应用很广。
展叶相对最晚的树种是()
A.梧桐
B.英国梧桐
C.泡桐
D.海桐
— The physics exam is not difficult, is it?—()Even Harry to the top students failed in it.
A.Yes;belongs
B.No;belonged
C.Yes;belonging
D.No;belonging