Bạn tham khảo đáp án của mình nhé:

Here are the completed sentences:

1. It lacks person-to-person interaction because participants cannot use body language or facial expressions. (This sentence explains why online communication might be less effective than face-to-face interaction.)
2. A live lesson can be affected by technical problems, such as hardware, software, or network failure. (This sentence highlights potential challenges during live online lessons.)
3. Video conferencing systems often have a certain limit on the number of participants. (This sentence points out a limitation of video conferencing technology.)
4. We need to invest in the quality of our devices and internet connections. (This sentence proposes a solution to improve online communication experiences.)