重介质选煤厂普遍采用磁铁矿粉作为加重质。
参考答案:对
----Where ____ the dictionary? I can't see it anywhere.
----I ____ it right here. But now it's missing.
A.did you put; have put
B.have you put; put
C.had you put; was putting
D.were you putting; have put
下列关于气温变化的叙述,正确的是[ ]
A.随海拔的升高,气温逐渐升高
B.海拔每升高1000米,气温升高约60℃
C.同纬度地带高原比平原气温低
D.赤道地区从山麓到山顶气温变化小