问二道英语的时态填空大家来看下吧

问二道英语的时态填空大家来看下吧
As the saying ----(go),a friend in need is a friend indeed.
这句话我不知道 填的是什么,是怎么看的是因为后面的a friend 单数 才用goes吗?
He is very hungry. He -----( not eat ) anything for three days.
这句话后面的 for three days 到底是指的是 现在完成时 还是一般过去式?
Look, the children -----(play) basketball on the playground .
这道题怎么做啊 时态没说啊,是现在还是将来啊