Every year thousands of trees _________ to improve the environment.
A:were planted
B:are planted
C:have planted
D:will plant
下列词语中加线字的读音,完全正确的一项是( )。
(1) She bought a ____ (bath) suit last Sunday.(2)I like doing some ____ (shop) at weekends.(3)She hasn't ____ (feed) the cat yet.(4)There are about ten ____ (well) in that village.(5)Has the camera been____ (pack) yet?
圆锥的底面半径是10cm,高是2cm.
①这个圆锥的底面周长是____;
②这个圆锥的底面积是____ cm2 ;
③这个圆锥的体积是____ cm3
视觉让你能够看到周围的事物,感知美好的世界,人的视觉的形成于( )
图中的新鲜土豆片与H2O2接触后,产生的现象及推测错误的是( )