题目内容
混凝土的黏聚性是指混凝土拌和物在施工过程中组成材料之间的黏聚力。( )
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凡工程结构用混凝土均应有配合比申请单和试验室签发的配合比通知单。( )
轻骨料混凝土的砂率应采用体积砂率表示，即细骨料体积与粗细骨料总体积之比。( )
对混凝土拌和物流动性大小起决定作用的是加水量的大小。( )
In the 1950’s, accumulating scientific evidence (26) cigarette smoking and lung cancer made a (27) impact (28) the smoking public. During this period many health agencies declared smoking to be a (29) hazard. US Surgeon GeneralLeroy E. Burney said in 1957, "The weight of the evidence is increasingly pointing to one direction: that (30) smoking is one of the causative factors in lung cancer." The initial reports had the heaviest impact, so (31) total cigarette production (32) in 1953 and again in 1954. (33) reports appeared to have less (34) on smoking habits, and by 1957 cigarette production had (35) above the 1952 level. (36) four voluntary health organizations (37) president John F. Kennedy to (38) a commission to study the widespread implications of the tobacco problem, the Surgeon General’ s Advisory Committee on Smoking and Health was (39) in 1962 to review and evaluate all (40) scientific data. When its report, Smoking and Health, was released in early 1964, cigarette (41) again declined (42) . Pipe and cigar smoking increased. More than 350 000 copies of the report were (43) and sold. (44) abstracts and pamphlets were prepared by the Public Health Service and other organizations (45) a massive educational campaign on the hazards of cigarette smoking.
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