While he___(sleep),the monkeys came down from the tree and took all his hats.填所给词语的正确形式填slept行吗,答案是was sleeping,求讲解.

While he___(sleep),the monkeys came down from the tree and took all his hats.填所给词语的正确形式填slept行吗,答案是was sleeping,求讲解.
While he___(sleep),the monkeys came down from the tree and took all his hats.填所给词语的正确形式
填slept行吗,答案是was sleeping,求讲解.

While he___(sleep),the monkeys came down from the tree and took all his hats.填所给词语的正确形式填slept行吗,答案是was sleeping,求讲解.
句子意思应该是:
当他正在睡觉的时候,猴子从树上下来,拿走了他的帽子.
这里强调一个正在进行的动作.

slep不行，此处表示当时正在。。。

Are there any monkeys in the tree? There aren't any monkeys in the tree.