细胞间何种连接最牢固（）。
A.紧密连接
B.中间连接
C.桥粒
D.缝隙连接
E.半桥粒
参考答案：C
In Hangzhou Mr Green was so struck ____ the beauty of nature that he stayed ____ another night.
A．at;on
B．with;at
C．for;in
D．by;for
所有上市交易的股票和债券都是证券经纪业务的对象。( )
