再生障碍性贫血
参考答案:
是由多种因素引起的骨髓造血功能衰竭,亦称骨髓衰竭性贫血。临床上以进行性贫血、出血、感染和全血细胞减少为主要表现。发病以青壮年居多,男性多于女性。
—Did you have any difficulty catching yesterday’s lecture?
—No. The professor spoke very clearly to make his speech easy _____.
A.understood
B.understanding
C.to be understood
D.to understand
ZX7-400型某弧焊机的额定负载持续率为60%,国家标准规定,手弧焊机的一个工作周期为5min,试问在一个工作周期内,焊机在额定焊接电流工作时的负载时间和空载时间各为多少?