如果你有了港口，那你就必须有一支海军。

If you're going to have a port, then you have to have a navy.

youdao

然而，姚明必须证明他的健康值得任何一支球队花数百万美元的风险。

However, Yao will have to prove his health is worth the multi-million dollar risk any team will be taking.

youdao

现在你必须躺下，立刻把脚支起来。

You have to lie down and put your feet up right now.

youdao

Now, the polio vaccine that Salk produced was very effective, but it required a fairly large dose of the vaccine and it had to be injected into the arms of children.

索尔克生产的小儿麻痹症疫苗效果显著,但是,该疫苗的单支注射剂量非常大,而且必须通过小孩的手臂进行注射

耶鲁公开课 - 生物医学工程探索课程节选