I can see a book on the desk,a clock（）the book and a pen（）th

I can see a book and a pencil on the desk 改成否定句 i have a book on the desk （A）clock and（an）English book are on the computer desk.为什么要用A There is a book and a pen on the desk.(变为否定句) a book and a pen is on the desk.对吗,为什么? _______ clock and a pen __________ on the desk.A.An,is B.A,i can you see a pen on the desk? A book and a pen____ on the desk. There are a book and a pen on the table. There( ) a pen and a book on the tabie . I can see a clock(on the wall).对括号里的部分提问 Look at your book改为 There( are )(a book)and (two pens)(on) the desk