小麦播种时,土壤耕层水分应保持在田间持水量的()。
参考答案:75-80%
The news of the mayor’s coming to our school for a visit was _______ on the radio yesterday.
A.turned out
B.found out
C.given out
D.carried out
低温容器用钢应考虑钢材的低温脆性问题,选材时首先要考虑钢的冲击韧性。