题目

Do you often help your father ___ the farm work during the summer vacation? A. for   B. on    C. in    D. with 答案：D 解析: with 在…方面,又如: she has to help with the washing.（2010•文山州）下列运算正确的是（ ）A．a2•a3=a5B．（ab）2=ab2C．（a3）2=a9D．a6÷a3=a2