they use oxygen far more effectively than Maiacetus. 它们利用氧气的效率远高于慈母鲸
He doesn't just use his to catch crabs. 它不光用颌来抓螃蟹
Some fish use them to protect their eggs. 有的鱼用颌来保护自己的卵
But worldwide only three percent of farmers have use of a tractor. 但是世界上仅百分之三的农民使用拖拉机
I use them to keep the bugs off the produce, 我种了用来驱虫的