Поставьте глаголы в нужную форму: 1. if you (to help) me,i (to finish) this work in no time. 2. helen is sure to lose weight if she (to keep) to a diet. 3. if you (not to put) on warm coat,you (to catch) a cold. 4. if mother (to buy) a cake,we (to have) a very nice party. 5. you (not to get) good marks,if you (not towork) hard.

1) If you help me, I`ll finish this work.
2) Helen is sure to lose weight if she keeps to a diet. 
3) If you don`t put on warm coat, will catch a cold.
4) If mother buys a cake, we`ll have a very nice party.
5) You will not (или won`t) get good marks. if you don`t work hard.
если Вы забыли во 2 предложении поставить в скобки (to lose), тогда предложение будет таким  Helen is sure will lose weight if she keeps to a diet.