—Is my clock on the table?
—No, _________. It's under the chair.
A:isn't
B:it isn't
C:it is not
D:it is
Lucy writes as ______ as Lily. They are both good students.
在花的结构中,最主要的部分是( )
芦苇是我国重要的造纸原料,但多数芦苇植株较矮、纤维短,影响产品的质量。如果想使芦苇植株长高,获得较长纤维,可用某一植物生长调节剂处理生长初期的芦苇,这一调节剂应该是( )