Sure! Here are the completed sentences for both sections:

### Practice 4: Complete the sentences using the given words/phrases

1. The doctors **operate on his eyes** half an hour till now.
2. It’s **hard for the old couple to get by** their small pension.
3. I **understand spoken English** often difficult; there are lots of varieties of English.
4. Once I **put the new system in**, I use it to increase productivity.
5. British English and American English **have some differences in vocabulary**.
6. His way of going over his lessons **has nothing in common with mine**.

### Practice 4: Complete the sentences using the word in the bracket

1. Jack spoke enough Chinese to communicate during his holiday. **(get)**
2. I share a lot of interest with my new roommate. **(common)**
3. The sun **owes** us almost everything in this world. **(owe)**
4. To be honest, I can't get what you are saying. **(truth)**
5. Flooding is one of the causes of crop loss in this area. **(contributes)**

If you need any further assistance, feel free to ask!