我小时候能一口气游完整个游泳池。

When I was little, I ___could swim across the whole pool without stopping.

你能帮我拿一下那个包吗？

___Could you help me carry that bag?

如果明天不下雨，我们可以去公园野餐。

If it doesn't rain tomorrow, we ___could have a picnic in the park.

这个周末可能会有雨，所以我们最好带上雨伞。

It ___could rain this weekend, so we'd better bring umbrellas.