左、右主支气管有哪些区别?其临床意义是什么?
参考答案:
左主支气管细、长,走向较平直;右主支气管短、粗,走向较垂直,气管异物易进入右主支气管。
It is uncertain ______ side effects these weight-loss drugs will bring about, although hundreds of thousands of patients have taken it.
A.that
B.whether
C.how
D.what
水平冰面上有一重为200N的雪橇,受到的拉力为35 N,方向与水平面成30°角.请在图中画出雪橇所受到的拉力的示意图.