正常心跳的起搏点是
A.心房肌B.窦房结C.蒲肯野纤维D.房室结E.房室束
参考答案:B
basketball is a good way to make us strong.
A.Play
B.Played
C.Plays
D.Playing
-- __________ beautiful city!
--Yes. Lots of tourists come to visit it every year.
A.How
B.What
C.How a
D.What a