6. You must read the instructions carefully, or you won't understand how to use this vacuum cleaner properly. (don't) You must read the instructions carefully, or you won't understand how to use this vacuum cleaner properly. 7. Although ordering food online is convenient, it can be more expensive and sometimes has delivery delays. (however) Although ordering food online is convenient, however it can be more expensive and sometimes has delivery delays. 8. It's a good idea to open a cafeteria in such a crowded street. (should) A cafeteria should be opened in such a crowded street. 9. Where do tornadoes mostly happen? (take) Where do tornadoes take place mostly? 10. Go to a public shelter if you feel it is unsafe to remain in your home. (unless) Go to a public shelter unless you feel it is safe to remain in your home. Exercise 11: 1. Remember to avoid using single-use products. 2. The forests will disappear if too many trees are cut down. 3. You should turn off devices that are not being used. 4. Water pollution affects marine life seriously. 5. Sellers often try to make the process of shopping online easier and more convenient. 6. Window shopping is one of my favorite activities when traveling to another city. 7. Ha Noi Night Market is a must-see place for visitors. 8. Because the weather was bad yesterday, they decided to go to the shopping center instead of the open-air market.