. Viết dạng đúng của từ trong ngoặc để hoàn chỉnh các câu sau. (0,8 điểm)

1. Isaac Newton is one of the greatest__________ in the history of human beings.            (physic)

2. The government has introduced some__________ measures to reduce unemployment. (effect)

3. You shouldn’t spend money__________ like that, please save for a rainy day.               (necessary)

4. I’m sorry that I have__________ what you said to me.                                                     (understand)