例：
Yesterday they climbed the mountain．
Now they are climbing the mountain．
Tomorrow they are going to climb the mountain．
（1）

Yesterday he read a book．

Yesterday he read a book．

Now he is reading a book．

Now he is reading a book．

Tomorrow he is going to read a book

Tomorrow he is going to read a book

（2）

Yesterday they had a picnic．

Yesterday they had a picnic．

Now they are having a picnic．

Now they are having a picnic．

Tomorrow they are going to have a picnic．

Tomorrow they are going to have a picnic．

（3）

Yesterday she drew a picture．

Yesterday she drew a picture．

Now she is drawing a picture．

Now she is drawing a picture．

Tomorrow she is going to draw a picture．

Tomorrow she is going to draw a picture．