Where were you at 7:00 last night? — I to my mom at home.

“Where is Tom?”–“He hasn’t come to school today, I think he ______be ill.”

Daming didn’t take a photo in the museum. I didn’t, .

We’ll go to Qing Yuan Mountain tomorrow. Why _____ join us? —That’s a good idea. [ ]

The harder we work, the_____ result we will get.