有利于改善复合树脂热膨胀系数应首选()
A.瓷粉
B.二氧化硅
C.硅酸铝锂
D.钡、锶玻璃粉
E.以上都不正确
参考答案:D
7位ASCII码共有多少个不同的编码值
A.126
B.124
C.127
D.128
25.He left for lunch________ the clock_________ twelve.
A.while; hit
B.immediately; struck
C.right away; beat
D.at once; knocked