用所给词的适用形式填空。

1.  We want two good ______ (music) for our club.

2.  Oh, dear! Can all the ______ (child) swim?

3.  He can help kids with ______ (swim).

4.  He ______ (want) to join the chess club.

5.  Mary sings very well.  I hope she will be a good ______ (sing).

构建股票投资组合的原因有二：一是为降低证券投资风险；二是为实现证券投资收益最大化。( )