我的笔掉到了抽屉的最底部。

My pen fell to the ___bottom of the drawer.

我们的帐篷搭在山谷的最深处。

We set up our tent at the very ___bottom of the valley.

我们公司在这个行业调查中排名垫底。

Our company ranked at the ___bottom in this industry survey.

宝宝坐在他的尿布上，保护他的小屁股。

The baby sits on his diaper to protect his little ___bottom.

我们需要找出这个问题的根本原因。

We need to find out the ___root cause of this issue.