Fill in the blanks with the correct verb forms: Countries which ______ still undergoing the economic processes ______ known as developing countries.

Introduction / Context:
This question tests your grasp of subject verb agreement and the correct use of auxiliary verbs in complex sentences. The sentence describes countries that are undergoing economic processes and states that they are known as developing countries. You need to choose the correct combination of verbs to keep the grammar accurate and consistent in number and tense.

Given Data / Assumptions:

• Sentence: Countries which ______ still undergoing the economic processes ______ known as developing countries.
• Options:
  • are, are
  • are, is
  • is, are
  • were, are
• Subject of the sentence is Countries, which is plural.
• The sentence talks about a present general truth regarding developing countries.
• The phrase still undergoing the economic processes works like a present continuous description.

Concept / Approach:
We must ensure that the verb agrees with the plural subject Countries and that the tense is appropriate for a general statement. The first blank introduces a present continuous passive like idea, so we expect are still undergoing. The second blank appears before known as developing countries, which describes the same plural subject Countries, so the verb must also be plural and present, that is are known. Both blanks must be filled with are to keep subject verb agreement and present tense consistency.

Step-by-Step Solution:
Step 1: Focus on the subject Countries. It is plural, so any present tense helping verb for this subject should usually be are, not is. Step 2: For the first blank, the sentence fragment is Countries which ______ still undergoing the economic processes. To form a continuous like description, we need are still undergoing, not is still undergoing. Step 3: For the second blank, read the remaining part: still undergoing the economic processes ______ known as developing countries. This clause still refers back to the same plural noun Countries. Step 4: The correct present passive form for a plural subject is are known, not is known, because is is singular. Step 5: Therefore both blanks must be filled with are, yielding Countries which are still undergoing the economic processes are known as developing countries.

Verification / Alternative check:
Check each option quickly: are, are → Countries which are still undergoing the economic processes are known as developing countries. Correct number and tense. are, is → The second verb is would mismatch the plural subject. is, are → The first verb is would mismatch the plural subject. were, are → Were suggests past time, which does not fit a general present truth. Only are, are produces a smooth, grammatically correct general statement about developing countries.

Why Other Options Are Wrong:
are, is: The second blank uses is known, which is wrong because Countries is plural. is, are: The first blank uses is still undergoing, which incorrectly pairs a singular verb with the plural subject Countries. were, are: Were indicates a past time frame, while the sentence talks about an ongoing general economic classification, so the tense becomes inconsistent.

Common Pitfalls:
A common mistake is to concentrate on only one blank and forget to check both for subject verb agreement. Another error is to be distracted by the phrase economic processes and think it controls the verb, but the actual subject remains Countries. Always identify the true grammatical subject and make sure each verb agrees in both number and tense.

Final Answer:
The grammatically correct sentence uses the pair are, are, giving Countries which are still undergoing the economic processes are known as developing countries.