Fill in the blank with the most appropriate word. In about forty years’ time we’ll probably _______________ on pills.

The correct answer is: A. be living

The sentence is in the future tense, so we need to use a verb that is in the future tense. The options A, B, and C are all in the past tense, so they are not correct. The option D is in the present perfect tense, but it does not make sense to say that we will have lived on pills in about forty years’ time. We will probably be living on pills in about forty years’ time.

Here is a more detailed explanation of each option:

• Option A: be living is the simple future tense of the verb “to live.” It is used to talk about things that will happen in the future. In this case, we are talking about something that will happen in about forty years’ time.
• Option B: have been living is the present perfect continuous tense of the verb “to live.” It is used to talk about things that have been happening for a period of time and are still happening. In this case, it does not make sense to say that we will have been living on pills for a period of time and are still living on pills in about forty years’ time.
• Option C: have been lived is the past perfect passive tense of the verb “to live.” It is used to talk about things that had happened before a certain point in time. In this case, it does not make sense to say that we will have been lived on pills before about forty years’ time.
• Option D: have lived is the simple past tense of the verb “to live.” It is used to talk about things that happened in the past. In this case, it does not make sense to say that we will have lived on pills in about forty years’ time.