Why didn’t you call me this morning?——I ______ call you. I called you all the morning, but I couldn’t ______.

______ Greens are on ______ visit to a beautiful city in China.

Robots ________ heavy work on farms in the future.

When I was a boy, I often ______ to play in that park.

This pair of jeans looks nice _______Lucy because she looks nice _______ blue.[ ]