为防止炉膛出口附近的受热面上结渣,应使炉膛出口烟气温度比灰的软化温度ST低()。
A.30-40℃;
B.50-100℃;
C.60-110℃;
D.100-150℃。
参考答案:B
It's four years since Mike _____ to Tibe. [ ]
A. has been
B. is coming
C. will come
D. came
适用于挖掘独立基坑、沉井,特别适于水下挖土的是()挖土机。
A.正铲
B.反铲
C.拉铲
D.抓铲