He had to double back to collect them.

他不得不原路返回，把它们取来。

The gymnast had to do a double back flip.

这个体操运动员得做一个360度后空翻.

The road ahead is flooded so we have to double back.

前面的路已遭水淹,我们只好原路折回.

It ruins a book to double back the pages as a bookmark.

把书页折起来当作书签用会把书弄坏的.

It is been the first double back flip in a wheelchair, it's being called that.

这是他在轮椅上第一次做出双后空翻。

He did not circle about topics, searching for the right phrase, or double back to restate a previous sentence.

他说话从不拖泥带水，已经说过的句子从不再重复，他不假思索就能找到合适的措辞。