问题
填空题
基本语法。
1. The streets here _____ (clean) by the cleaners every morning.
2. These flowers _____ (water) once every three days.
3. Many new things _____ (invent) by the scientists in the 20th century.
4. Yesterday a composition on protecting animals _____ ( write) by the students of our class.
5. The little girl had learned to play the piano _____ the age of five.
答案
1. are cleaned 2. are watered 3. were invented 4. was written 5. at