制作一个底面直径20cm、长50cm的圆柱形通风管,至少要多大的铁皮?
2×3.14×(20÷2)×50=3140(cm2)
土地征用
句型转换
1. Tom went to the zoo four times last year.(对划线部分提问)
Tom to the zoo last year?
2. Lily has eaten fish and chips.(改为否定句)
Lily fish and chips.
3. Mr. Liu began to teach English in 2005.(用现在完成时改写句子)
Mr. Liu English .
4. I knew Bob two years ago.(改为同义句)
I Bob two years.
5. Mr. Green has lived here since he was 12 years old.(对划线部分提问)
Mr. Green here?