It can be inferred from the passage that children normally learn simple counting ______. a. soon after they learn to talk b. by looking at the clock c. when they begin to be mathematically mature d. after they reach second grade in school

按倾斜状态不同分类，船舶稳性可分为（）。

Ⅰ、静稳性

Ⅱ、动稳性

Ⅲ、横稳性

Ⅳ、纵稳性

Ⅴ、初稳性

Ⅵ、大倾角稳性

A．Ⅱ+Ⅲ+Ⅳ

B．Ⅲ+Ⅴ

C．Ⅲ+Ⅳ

D．Ⅲ+Ⅴ+Ⅵ