当焊接预热焊件温度达()时,应设挡板隔离焊件发出的辐射热,焊接人员应穿戴隔热的石棉服装和鞋、帽等。
A.100
B.120
C.140
D.150
参考答案:D
When my cat is hungry, he _______ the cage door _______ his paw.
A.knocks on, in
B.knocks at, with
C.knocks on, by
D.knocks at, uses
根据微生物繁殖的特点,中药养护时可采用的既能杀虫、防霉,又能保持药材色、味措施为
A.通风法
B.干燥法
C.降氧
D.避光
E.充氧