高压电容器组和总容量在()kvar以上的低压电容器组每相应装电流表。
A、30
B、60
C、100
D、2000
参考答案:A
硫酸和硝酸是中学阶段常见的两种强酸,请就两者与金属铜的反应情况回答下列问题:
(1)在100mL 18mol·L-1的浓硫酸中加入过量的铜片,加热使之充分反应,产生的气体在标准状况下的体积可能是 (填写代号):
A.7.32L
B.6.72L
C.20.16L
D.30.24L(2)若使上述反应中剩余的铜片继续溶解,可向其中加入硝酸钠,写出反应的离子方程式 。
A little boy invited his mother to attend his school’s first teacher-parent meeting. To the little boy’s (1) , she said she would go. This (2) be the first time that his classmates and teacher (3) his mother and he felt (4) of her appearance. Although she was a beautiful woman, there was a severe sear (疤痕) that (5) nearly the entire right side of her face. The boy never wanted to (6) why or how she got the sear.At the meeting, the people were (7) by the kindness and natural beauty of his mother (8) the sear, but the little boy was still embarrassed (尴尬) and (9) himself from everyone. He did, however, get within (10) of a conversation between his mother and his teacher.The teacher asked (11) ," How did you get the scar on your face"The mother replied, " (12) my son was a baby, he was in a room that caught fire. Everyone was (13) afraid to go in because the fire was (14) , so I went in. As I was running toward his bed, I saw a long piece of wood coming down and I placed myself over him trying to protect him. I was knocked (15) but fortunately, a fireman came in and saved both of us. " She (16) the burned side of her face. "This scar will be (17) , but to this day, I have never (18) what I did. "At this moment, the little boy came out running toward his mother with tears in his eyes. He held her in his arms and felt a great (19) of the sacrifice (牺牲) that his mother had made for him. He held her hand (20) for the rest of the day.
第(15)空应选择()
A.helpless
B.hopeless
C.senseless
D.useless