中国古代的自耕农经济非常脆弱,主要受哪些不利因素的制约
①天灾人祸 ②人口增加 ③土地兼并 ④水利设施
A.①②
B.①③
C.②③④
D.①②③
答案:D
All the ___ in our school enjoyed themselves on March 8th because it was their own holiday.
A.women teachers
B.men teachers
C.woman teachers
D.man teachers
简述德育的认知模式。