tsuppose the police know who did it—-Well, surprisingly they do Aman has been arrested and _____ now

Steve isn’t as__________ as Kelly.He often makes mistakes in his writing.

Those ____ want to go please sign their names here.

下列各句中，没有语病的一项是（ ）

Experiments of this kind ________ in both the U. S. and Europe well before the Second World War.[ ]