先化简后计算:4(3a+b)-3(5a-2b),其中a=10,b=2.
原式=12a+4b-15a+6b
=-3a+10b,
当a=10,b=2时.原式=-3×10+10×2=-10.
I'd rather have a room of my own, however small it is, than ___ a room with others. [ ]
A. to share
B. to have shared
C. share
D. sharing
梨锈病为害叶片时在叶背产生灰白色的毛状物,此物是()。
A.性孢子器
B.锈孢子腔
C.冬孢子堆