最适宜于冬期施工用的混凝土外加剂是( )。
A.(A) 引气剂
B.(B) 减水剂
C.(C) 缓凝剂
D.(D) 早强剂
参考答案:D
________with what the students had done, the teacher praised them highly. [ ]
A. Delight
B. Delighting
C. Delighted
D. Being delighting
用浏览器访问FTP站点,应在地址前加入()标志。
A.http://
B.http.
C.ftp://
D.ftp.