If people continue cutting down trees, there would be a landslide near mountain. = If people continue cutting down trees, there will be a landslide near the mountain.
“would” → “will” because this is a likely future event; “near mountain” → “near the mountain” (need article).

Without trees on the mountain and forests, there would be no source to hold the water from rains. = Without trees on the mountain and in the forests, there would be nothing to hold the rainwater.
 “source to hold the water from rains” → “nothing to hold the rainwater” is simpler and more natural.

So if it rained so heavily, there would be a huge landslide and many people would be hurt. = So if it rains heavily, there will be a huge landslide and many people could be hurt.
“rained so heavily” → “rains heavily” for a general future possibility; “would be hurt” → “could be hurt” is more realistic.
 

ESSAY:

I think technology is like a double-edged sword in our lives. On one hand, it makes it easier to contact people regardless of distance and helps them share ideas and access education globally. On the other hand, easy communication can reduce face-to-face interaction and lead teenagers to rely heavily on digital devices. Despite these drawbacks, I believe the benefits outweigh the disadvantages because technology broadens the world and improves people’s lives. Moreover, we can address the disadvantages through thoughtful policies and careful efforts.

Your answer is very good because you explained both the advantages and disadvantages of technology and gave a clear opinion. To improve, try using more specific examples of technology in everyday life to make your answer more concrete. Also, when speaking, connect your ideas with linking words like “on one hand” and “on the other hand” to make your answer flow naturally.