12. It's great to have many friends, but it's more important to see (clear) who is truly helping you.
13. Our mother river has become much (clear) than before.
14. I hope it will clear this afternoon. Then we can clear the rubbish in the park.

12. clearly 13. clearer 14. up; up/out

15. The government has warned people not (believe) what they hear on the phone.
16. The Ministry of Education warns against (introduce) premade meals to schools.
17. (2026 南通一模)—Now too many teenagers have serious eye problems.
—They
(必须被警告要远离) electronic games.
变形：warn vt.&vi.→warning n.警示;警告;告诫
warn
vt.&vi.
警告，
告诫
warn sb (not) to do sth
警告某人（不要）做某事
be warned (not) to do sth
被警告（不要）做某事
warn sb of/about sth
提醒注意某事
warn (sb) against doing sth
警告（某人）不要做某事
warn + that 从句
警告/告诫……

15. to believe
16. introducing
17. must be warned to keep/stay away from

用when、while、as或所给动词的适当形式填空
After the hike, I 1. (walk) through a forest when I heard a strange noise. The wind 2. (blow) heavily, while the big snowflakes 3. (fall) from the dark sky. I 4. (look) for a place to hide 5. I saw a small cabin nearby.
When I entered the cabin, a kind man inside 6. (make) a warm fire. He invited me in.
语法点1:过去进行时
表示过去某一时刻正在进行的动作或过去某一阶段一直在进行的动作。 更多讲练见本册P179
语法点2:when、while和as的用法
(1)当某个动作正在进行时,又发生了另一动作,此时when、while、as都可以连接主从句,构成“一般过去时+when/while/as+过去进行时”结构。
(2)“过去进行时+when+一般过去时”结构
7. we were drinking hot coffee, he told me stories about the mountains. Outside, the storm was getting worse, but it was safe and cozy inside the cabin.
强调某个动作正在进行时,另一个动作突然发生。 更多讲练见本册P200

1. was walking 2. was blowing 3. were falling 4. was looking 5. when 6. was making 7. While/When/As