He . . . . . . . . an airplane for 10 hours. A. has flown B. is flying C. has been flying D. will fly

The correct answer is: C. has been flying

The sentence “He has been flying an airplane for 10 hours” is in the present perfect continuous tense. This tense is used to talk about an action that started in the past and is still happening now. In this case, the action is “flying an airplane”. The sentence tells us that the person has been flying an airplane for 10 hours, and is still flying.

The other options are incorrect because they do not accurately describe the action that is happening in the sentence. Option A, “has flown”, is in the simple past tense. This tense is used to talk about an action that happened at a specific time in the past. In this case, the sentence would mean that the person flew an airplane at some point in the past, but is not flying now. Option B, “is flying”, is in the present tense. This tense is used to talk about an action that is happening right now. In this case, the sentence would mean