对一个客观事物,可以用多种数据模型来描述。( )
参考答案:对
植物的双受精完成后,不能继续发育的结构是( )
A.子房壁
B.花柱
C.受精卵
D.胚珠
We have just heard a warning on the radio ________ an earthquake is likely to strike that area again.
A.which
B.what
C.that
D.when