四、阅读短文并填空
There is a busy world within every plant. Each part has a special job to do. Let's learn about their work.
It's quarter past seven now. The "workers" in the leaf are ready 1. (start) their work. The root 2. (collect) water and minerals from the soil every day. The water 3. (rise) up to the leaves through the stem. The leaves can 4. (mix) water, carbon dioxide and sunlight to make sugar. Sugar is very useful for the plant's 5. (grow). The plant 6. (produce) oxygen as a by-product. Oxygen 7. (mean) a lot to humans and animals. When it 8. (get) dark, the "workers" will take a rest. There are millions of 9. (plant) on Earth. Without plants, the natural world 10. (be) very different.

1. to start 2. collects
3. will rise/is going to rise 4. mix
5. growth 6. will produce/is going to produce
7. means 8. gets 9. plants 10. will be