用括号内所给单词的适当形式填空。
1. What will the weather_______ (be) like next Saturday?
2. —When _______ you _______ (arrive). 
    —Five minutes ago.
3. —Would you like _______ (go) skiing?
    —Good idea!
4. Bring your umbrella because it may _______ (rain) later.
5. It's a good way _______ (improve) your English study.