The economy produces three kinds of products: books, bread and string beans. Their production and prices in 1998 and 1999 are as follows  As shown in the table, try to find.

(1) Nominal GDP in 1998

(2) Nominal GDP in 1999

(3) Taking 1998 as the base period, what is the real GDP in 1998 and 1999 and what is the percentage change of the real GDP in these two years?

(4) Taking 1999 as the base period, what is the real GDP in 1998 and 1999 and what is the percentage change of the real GDP in these two years?

(5) Is it true that "the change of GDP depends on the price of that year as the base period for measuring real GDP"?