按形态可将礁分为哪些类型?
参考答案:
①点礁,也称斑点礁;
②宝塔礁,也称尖柱礁或孤礁;
③马蹄形礁,也称新月形礁;
④环礁;
⑤丘礁;
⑥层状礁。
—Can you ride a horse?
—No, I ______. [ ]
A. needn't
B. may not
C. can't
D. mustn't