The reading section of the gaokao English paper is a time problem before it is a comprehension problem. Students who understand every word but read every word twice run out of clock.
For each passage, spend about twenty seconds on the first and last sentence of every paragraph. That gives you the skeleton of the argument. Then read the questions, and go back into the passage only where a question sends you.
'Main idea' answers are nearly always a paraphrase of the first or last paragraph. If an option paraphrases a detail from a middle paragraph, it is probably a distractor.
On inference questions, be conservative. The right answer goes only slightly beyond what the passage actually says. An option that makes a big leap is wrong, however insightful it sounds.
For vocabulary-in-context questions, drop each option into the original sentence and check that it still fits the argument of the passage. Do not rely on the dictionary meaning you memorised.