A:灵渠
B:京杭大运河
C:巴拿马运河
D:苏伊士运河
Clerk: ____ I help you?
Mary: Yes, please. I want a sweater.
Clerk: What ____ do you want?
Mary: Blue.
Clerk: Here you are.
Mary: How ____ is it?
Clerk: Nine dollars.
Mary: I'll ____ it. Thanks.
Clerk: You're ____.
传染病和非传染病不同,传染病具有____ 的特点。传染病能够在人群中流行,必须同时具备____、____ 、____ 这三个基本环节,缺一不可。
下列化学物质中,不是植物激素的是( )
Are these ____maps? Yes, they are. ( )
____