冠心病心绞痛患者至少有一个冠状动脉的主支管腔显著狭窄达横截面积的()
A.30%以上
B.50%以上
C.75%以上
D.90%以上
E.95%以上
参考答案:C
________ has been mentioned above,continued chairman after he took a sip of coffee,________ the project must be carried out before spring flood comes.
A.As;that
B.That;which
C.This;which
D.It;that
为了促进光合作用,增加农作物的葡萄糖含量,要把蔬菜大棚内空气中二氧化碳浓度提高,同时降低氧气含量,应在大棚内采取的正确措施是 [ ]
A.点燃红磷
B.点燃硫磺
C.点燃木炭
D.堆放氢氧化钙