I am doing sums.

Sums are done by me.
Sums are being done by me.
I must be doing the sum.
Sums must be done by me.

The correct answer is: I am doing sums.

The other options are incorrect because they do not accurately reflect the meaning of the sentence.

  • Option A, “Sums are done by me,” is incorrect because it implies that the sums are already complete, while the sentence states that the speaker is in the process of doing them.
  • Option B, “Sums are being done by me,” is incorrect because it implies that the sums are being done by someone else, while the sentence states that the speaker is doing them themselves.
  • Option C, “I must be doing the sum,” is incorrect because it implies that the speaker is obligated to do the sum, while the sentence does not state this.
  • Option D, “Sums must be done by me,” is incorrect because it implies that the sums are required to be done by the speaker, while the sentence does not state this.

The sentence “I am doing sums” is in the present tense and active voice. It states that the speaker is currently engaged in the activity of doing sums. The sentence does not specify what type of sums the speaker is doing, or how many sums they are doing.