【简答题】What is Macyn ’ s favorite sport and why does she like it?
【单选题】— What about the protection? — Let's keep the surface ________ dirt by putting a cover on it. [ ]
【单选题】What's the main idea of the second paragraph?______
A.
Fossil energy was once very cheap
B.
Farms in dry areas could get cheap water
C.
Most American farmers used too much fertilizer and pesticide
D.
Mainstream American agriculture used to be wasteful of energy, water and land
【单选题】断路器除满足正常工作条件外,还要求它能可靠地切断最大短路电流。一般用( ) 来表示断路器开断短路电流的能力.
【判断题】964在空载状态下,驻车制动装置应能保证机动车在坡度为20%、轮胎与路面间的附着系数不小于0.7的坡道上。( )
【判断题】在“无限大容量的电力系统”中,短路全电流的最大有效值,是短路后第一个周期的短路全电流的有效值,一般用Ish表示,它也可称为短路冲击电流有效值。( )
【简答题】下图为裸子植物生活史示意图,请填入序号对应的世代名称或结构名称,并填空回答下列问题。 ①裸子植物________发达,其强壮的茎中有高度分化的__________组织,茎干也有加粗的次生生长。 ②裸子植物有性生殖时受精作用在__________中进行,受精卵发育形成为_________。由于_________及_________裸露,没有真正的花和果实。 ③裸子植物单性的孢子叶聚集成球花或球果,雌...
【单选题】—What's the matter with you, Lucy? —After the long walk, my legs ___________ and I couldn't go any farther.