A:4和6
B:3和1
C:2和4
D:1和2
完型填空。
I am 1English boy. My 2is Mike. I am twelve. My sister's name is Ann and we are students. My mother3a teacher. She's a Chinese teacher. My brother's name is Jim. He's five.4 father isn't here. He's 5Xinjiang. I think my family is a good one.
比一比,再组词
仍____ 抽____ 钱____
扔____ 油____ 线____
甲 乙 丙
原式=a2+2ab﹣(a2﹣b2) (第一步)
=a2+2ab﹣a2﹣b2(第二步)
=2ab﹣b2 (第三步)
用元素符号或化学式填空:
(1)3个氮分子 ____
(2)4个硫离子 ____
(3)n个铜原子 ____
(4)正五价的磷元素 ____