板桩式围护结构可分为( )。
A．钢板桩
B．钻孔灌柱桩
C．钢管桩
D．主桩横挡板
E．钢筋混凝土板桩
参考答案：A,C,D,E
催化脂肪酸合成的限速酶是
A．HMGCoA还原酶B．HMGCoA合酶C．HMGCoA裂解酶D．乙酰辅酶A羧化酶
Risk of collision may exist（）.
A.if the compass bearing of an approaching vessel does not appreciably change
B.even when an appreciable bearing change is evident, particularly when approaching a vessel at close range
C.if you observe both sidelights of a vessel ahead for an extended period of time
D.All of the above
