【简答题】由于地下水位持续过高或因土壤土质粘重,使土壤根系活动层含水量过大,造成作物根系活动层中的水、肥、气、热失调,而导致农作物减产的一种灾害叫 ( )
【单选题】This passage is mainly about ______.
A.
the structure of poetry
B.
the components of poetry
C.
the nature and importance of poetry
D.
the appreciation of poetry
【单选题】What leads to the formation of a black hole?
A.
The structure of a star.
B.
A collision between two stars.
C.
The attraction of two large stars.
D.
The shrinking of a large star by its own gravitational force.
【判断题】液压缸的活塞上开环形槽,可减小径向不平衡力。 ( )
【简答题】歌曲《唱支山歌给党听》是怎样诞生的?和雷锋有什么关系?