They/ not answer/phone/ this morning, so/ must/ out/. They hasn't answered the49/50Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is best made up from the prompts. They/ not answer/phone/ this morning, so/ must/ out/.They hasn't answered the phone this morning so they must have been outThey didn't answer the phone this morning so they must be outThey didn't answer the phone this morning so they must have gone outThey hasn't answered the phone this morning so they must go outGiải thíchChọn D