The term PROLONGED BLAST refers to().
A.a blast of from five to seven seconds' duration
B.a blast of from five to six seconds' duration
C.a blast of from four to six seconds' duration
D.a blast of from six to seven seconds' duration
参考答案:C
The term PROLONGED BLAST refers to().
A.a blast of from five to seven seconds' duration
B.a blast of from five to six seconds' duration
C.a blast of from four to six seconds' duration
D.a blast of from six to seven seconds' duration
参考答案:C