齿轮泵困油现象的产生原因是(),会造成(),解决的办法是()。
参考答案:齿轮重合度大于1;震动和噪音;在泵盖上加工卸荷槽
If we _____ nothing, there _____ fewer and fewer tigers in the world. [ ]
A. will do; will be
B. do; will be
C. don't do; will be
D. do; will have