问题 选择题

金属的下列性质不能用金属晶体结构加以解释的是( )

A.有金属光泽

B.易生锈

C.易导电

D.有延展性

答案

答案:B

金属晶体中金属阳离子紧密堆积,自由电子在整个晶体里自由移动。在外加电场的作用下,自由电子可以发生定向运动;受到外力作用时,金属晶体的各原子层发生相对滑动,但金属离子与自由电子的相互作用并没有改变。故金属晶体一般有光泽,能导电,具有延展性。并不是所有的金属都易生锈,生锈是金属原子失去电子被氧化为金属阳离子的过程,发生氧化还原反应。

填空题

Part 4


Questions 26-45


·Read the following article and choose the best word for each space.
·For questions 26-45, mark one letter A, B, C or D on the Answer Sheet.

iPhone Left in Hot Car for Three Hours


The normally peaceful suburban town of Winnetka is still reeling following the news Monday (26) a local resident, whose name is being (27) by police pending a full investigation, left an iPhone unattended for more than three hours in a car (28) in the hot sun.
"Responding to calls from (29) . passersby, who observed the iPhone sitting in a vehicle in the parking (30) of the Westfield Shopping Center, police arrived on the (31) at approximately 4 p.m. and immediately intervened to save the device," said Winnetka police chief Douglas Blaine. "Security cameras have shown that the iPhone had been in the car— with the doors (32) and the windows rolled (33) —since 1 p.m. Due to the tragic and highly emotional (34) of this case, we cannot say any (35) at this time."
According to official police records, two officers forcibly (36) into the car at 4:07 p.m. and found the iPhone (37) face down on the dashboard. The iPhone at first showed no (38) of life, but after a tense few seconds, officers were able to wake it and get it to (39) to a series of simple touch commands. Police said that if the iPhone were left in the extreme (40) for any longer, it could have died.
The iPhone was rushed by ambulance to a nearby Apple facility for careful (41) .Miraculously, no damage to its memory, screen, or wireless capabilities was reported.
Upper-middle-class suburbanites from all over the North Shore area have reacted to the near-tragedy with an unprecedented outpouring of (42) . Hundreds of cards and letters have come streaming in, and local talk radio shows have been flooded (43) calls demanding that the iPhone’s (44) be prosecuted. Many have come forward offering to take the iPhone into their custody, and still (45) have donated free downloads, ringtones, and MP3s to the victimized object.

A.parked

B.driven

C.sold

D.washed

判断题