Do you think necessary to do a bird count ?
Yes , we must count them at least once a year
| A． it | B． that | C． we | D． they |
My little brother caught a cold, ________ he didn’t wear warm clothes yesterday.
| A．so | B．because | C．but | D．and |
I couldn’t work out this problem ________ my teacher helped me.
| A．before | B．unless | C．because | D．until |
_________ my mother was washing clothes, my father was reading books.
| A．While | B．When | C．Before | D．After |
When the first ______ came to the US, they were hungry as they have nothing to eat.
| A．students | B．pioneers | C．heroes | D．soldiers |
Spring is the best _______ of the year, because we can see lots of beautiful flowers.
| A．date | B．day | C．season | D．vacation |