采用通天抱杆起吊单杆时,电杆长度不宜超过()m,电杆绑扎点不得少于2个。
A.15
B.18
C.21
D.24
参考答案:C
After _____ seemed an hour or so, we were able to enter the pavilion.
A.it
B.when
C.which
D.what
下列哪项不是诊断二度慢性放射病的条件()
A.长期射线接触史
B.乏力、头痛、头晕等自觉症状
C.有明显出血倾向
D.白细胞在稳定减少在3.0×109以下,骨髓增生活跃
E.治疗后恢复缓慢