---The box is too heavy to carry. What’s in it? ---Oh, I _________ it ________books.
Are you going to __________ this challenge?(挑战)
The boy looks nice ________ white and the red sweater looks good ________ the girl.
We just need one of you for the game.________you _______your brother can join us.
--- Cross the road carefully, __________ you’ll keep yourself safe.--- Thank you.
---Why do you like yellow?--- Because it always reminds me __________ a warm, sunny day.