______ number of boys were swimming in the lake, but I didn’t know ______ exact number of them. A. A/the B. The/an C. The/the D. A/anĐoạn văn75/320______ number of boys were swimming in the lake, but I didn’t know ______ exact number of them. A/the The/an The/the A/anGiải thíchĐáp án A