关于化学键的下列叙述中,正确的是 [ ]
A.离子化合物可能含共价键
B.共价化合物可能含离子键
C.离子化合物中只含离子键
D.离子化合物中一定含有金属离子
答案:A
Children brought up in cities are often full of ____ about beans, pens, cucumber, eggplant, mushrooms,
carrots. [ ]
A. curiosity
B. fantasies
C. ideas
D. imagination
-7ab-14abx+49ab=-7ab( )。