蚕豆病3岁以上儿童占病例的比例为()
A.80%
B.60%
C.50%
D.70%
E.40%
参考答案:D
I keep in touch with the friend ______ who stands ______ to me.
A.close; closely
B.closely; close
C.close; close
D.closely; closely
某机器中码字长15位(包括信息位和海明校验位),采用了可纠正一位错的海明校验。识码字位从左到右用b1, b2…b15编号,其海明校验方程式为 b1b3b5b7b9b11b13b15=0 b2b3b6b7b10b11b14b15=0 b4b5b6b7b12b13b14b15 =0 b8b9b10b11b12b13b4b15=0 若在选项中给出的码字最多只有一位错,那么第2位b2错的码字为 (29) ;无错的码字为 (30) 。
A.010100101111110 B.000100101101010C. 010111011101010 D.011011101101010