Replace the adverbial clauses of time by the Participle

Model: When you speak English, pay attention to the intonation.

(When) Speaking English, pay attention to the intonation.

1. Be careful when you cross a street. 2. When you leave the room, don't forget to switch off the light. 3. When you begin to work with the dictionary, don't forget my instructions. 4. When they were travelling in Central Africa, the explorers met many wild animals. 5. When you copy English texts, pay attention to the articles. 6. You must have much practice when you are learning to speak a foreign language.