18. My mother ____ for Beijing in a few days. I wonder when the earliest plane ____ on Monday?
______more information ,write to the address below.
If you______the right map , we wouldn’t have got lost.
—Which umbrella can I take? —You can take______of them; I will use none.
Living in the desert involves a lot of problems,______water shortage is the worst.
Only when you have obtained enough data______ come to a sound conclusion.