It was        Asimov was eleven years old        his talent for writing                        became obvious.

A．that, when

B．When, which

C．when, when

D．when, that

在风景园林构成要素中，（）是风景园林规划设计的基础，是构成园林景观的骨架。

A.园路及铺地

B.地形

C.水体

D.植物