6.He gave me a________ (mean)glance.　

答案：1.operations　因为在句子中作主语，所以要用名词形式，根据后面的系动词are,要用名词的复数形式。　

5.The case of________ (blind)is very special.　

4.The doctor’s________ (treat)cured him.　

3.Most of the Americans use their cars________ (most)for their job.　

2.His________ (ill)is serious.　

1.The _________(operate)are very successful.　

6.Many astronauts have already visited the space station.

5.The spacecraft has just reached the moon.　

4.They haven’t been to Mars yet.　我们在学现在完成时的时候,经常会出现already,just,yet这三个词,它们在句中的位置分别是already,just放在have/has与过去分词之间,yet放在句末。其意分别为“已经,刚刚,还”。　

3.Scientists haven’t found life on other planets.　现在完成时的否定式是在have/has后直接加上not。