Choose the correct option to complete the following sentence:
The higher you go, the more difficult it_____ to breathe.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → becomes
"The + comparative ..., the + comparative ..." for a general truth:
- The pattern "the higher ..., the more difficult ..." shows that two things change together.
- When it states a general truth, both clauses take the simple present.
- Clue word: the first clause has the simple present "you go", and the sentence states a fact that is always true at high altitudes, so the second clause needs "becomes".
- Complete sentence: The higher you go, the more difficult it becomes to breathe.
Example: The longer you wait, the harder it becomes.
Why the Other Options are Incorrect?
Option 1: has become — Incorrect. The present perfect describes a change completed up to now; it does not state a general truth and does not pair with "you go".
Example: It has become cold since evening.
Option 3: was becoming — Incorrect. The past continuous describes something in progress at a time in the past; it clashes with the present "go".
Example: It was becoming dark when we reached home.
Option 4: became — Incorrect. The simple past reports one past event, not a general truth.
Example: He became a doctor in 2020.
Contrast: the simple present states a general truth ("it becomes"); the present perfect, past continuous and simple past tie the change to a particular time.