各种作物的理想株型一般是中偏矮秆或是半矮秆且具有()的叶层配置的品种。
参考答案:倾斜
食管癌进食困难术前应采取下列哪项有效营养支持途径()。
A.胃造瘘营养支持
B.肠外营养
C.经口营养支持
D.鼻饲营养支持
E.空肠造瘘营养支持
N—S diagram can used to substitute conventional program flow chart. In the following phrases, which does not belong to the basic control structures that contain ( )
A.sequence structure
B.condition structure
C.selection structure
D.execution structure