将一个三角形木块水平放置，其平面直观图是如图所示的腰长为1的等腰直角三角形，则这个木块的面积是（　　）

图甲是显微镜的结构图，图乙、图丙是两种细胞结构模式图，据图回答（    内填数字，横线上填文字，示例：⑥载物台）

根据句意，用括号中所给单词的正确形式填空。
①The new students had always lived with their parents before they came here. They are not used to____  (be) away from home.
②Antonio is liked by everyone because he is always ready ____ (help) others.
③Teenagers should ____  (allow) to go out with their friends.
④We hope the weather will be fine, but it is getting even____ (bad).
⑤He believed his lucky number was 12, so he decided to live on the ____  (twelve) floor.
⑥Timmy has spelt the name____  (correct). That’s why his friend can’t find him easily.
⑦I wonder if there are any____ (suggest) about how to learn English well.

雨育农业是在干旱、半干旱或半湿润易旱地区完全依靠天然降水从事作物生产的一种栽培制度。图为世界某区域示意图，读图回答下列问题。

关于声现象的说法，不正确的是（ ）