钻削时,切削热传出途径中所占比例最大的是:()
A、刀具
B、工件
C、切屑
D、空气介质
参考答案:B
用括号中所给词的适当形式填空。
1. You should be much . It's good for your health. (health)
2. Recently I listened a song Heart Strings. (call)
3. He told me that he in that school for 10 years. (teach)
4. I've been (try) to cheer him up for 20 minutes.
5. The telephone (invent) before the car.
哪些情况下应禁行消化道钡餐检查?