根系对水分的吸收能力弱,但需水量大,需要较高的土壤湿度和空气湿度的蔬菜有()
A.白菜
B.绿叶菜类
C.甘蓝
D.黄瓜
E.茄果类
参考答案:A, B, C, D
Object-oriented analysis(OOA)is a semiformal specification technique for the object-oriented paradigm. Object-oriented analysis consists of three steps. The first step is (71) . It determines how the various results are computed by the product and presents this information in the form of a (72) and associated scenarios. The second is (73) ,which determines the classes and their attributes. Then determine the interrelationships and interaction among the classes. The last step is (74) , which determines the actions performed by or to each class or subclass and presents this information in the form of (75) .
74()
A.use-case modeling
B.class modeling
C.dynamic modeling
D.behavioral modeling
当AM的调制度m≤1时,m越大,则()。
A.信号功率越大
B.信号功率越小
C.信号功率不变