石油沥青的熬制时间宜控制在(),确保脱水安全。
A.1~2h
B.2~3h
C.3~4h
D.4~5h
参考答案:D
They are very _ . that their daughter can cook dinner for them.[ ]
A. surprise
B. surprised
C. surprising
D. surprises
确定杆塔外形尺寸的基本要求有哪些?