---Why is the little boy crying over there?
-----He is too short to reach ___ the toy bear  ___ the toy car on the shelf?

We arrived ______ late that there were no seats left.

My sister ______ go to bed _______ my mother came back last night.

— Would your brother go for a picnic?. —If I don’t go, __________ .

--- This history book is of great value.
--- Exactly. ____________ can be enjoyed from it ____________ you have a deep understanding of it, however.

        they are twins, they don’t look the same at all.

We still gave the boy another chance ______he made some mistakes.

---We can’t get good grades ______ we study harder.
---I agree. That’s why I study so hard.
A. because                  B. if                       C. unless

– How long have you been collecting stamps?
–         I was ten years old.
A. Since                        B. When                 C. Because

More historical buildings in the old town will fall down ________we try our best to protect them.