Continuous short buzzes on the telephone indicate that the line is busy after you dial the telephone number.
A. open
B. out of order
C. disengaged
D. in use
It is necessary for technicians ______ one or two foreign languages.
A. master
B. to master
C. mastering
D. mastered
油脂性基质栓应在多少分钟内全部融化、软化,或触压时无硬心( )
A. 40
B. 20
C. 30
D. 10
E. 60
Don't hazard your reputation by supporting his joint venture with the gay from Los Angels.
A. adventure
B. risk
C. threaten
D. venture