__________ we conserve natural resources, they will run out very soon.
A. If
B. Unless
C. Whether
D. In case
Đáp án: B
Giải thích: unless = if…not…: trừ phi
Dịch: Nếu chúng ta không bảo tồn tài nguyên thiên nhiên, chúng sẽ cạn kiệt rất nhanh
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Without plants, most water ____________ off as soon as it falls, taking away valuable soil.
Man and most animals need a _____________ supply of water to live.
There are about 3,000 plants __________ values as medicines against cancer, AIDS, heart disease and many other sicknesses.
Both fossil fuel _______ non-renewable resources are very important to our life.
To save electricity, we are cutting down __________ our central heating.
Deforestation _________ destroying Earth’s plant and animal variety.
Each year about fifty hundred_________ of plants and animals are already being eliminated.