题目

This column is part of a series on websites that are useful for English language learning. Activities for ESL Students Includes various types of tests, exercises and puzzles designed to help people studying English as a second language （ESL）.The activities include grammar, vocabulary and idiom tests at easy, medium and difficult levels. The specially designed Chinese-English vocabulary tests can help Chinese memorize English words. http://a4esl. org/ Interesting Things for ESL Students Contains a comprehensive list of audio clips（听力剪辑）from the Special English programs —Do you plant trees in spring, Mike?—Yes. Many trees ________ in our city every year.A.plantB.are plantingC.have plantedD.are planted