很简单的,总之就是把动词换成过去分词,再在前面加上be动词,be动词的形式根据主语的数、人称和时态作相应改变即可。
比如,I am punished today./She is punished today. 这里am与is的区别就看前面主语是谁了。
The flowers are watered today./The flowers were watered just now.这里面watered是动词的过去分词,不变,就看时态是什么了,如果是现在就用are,是过去就用were.
温馨提示:内容为网友见解,仅供参考