–Why, David, you look so tired!

–Well, I ______ a report for the whole day and I must finish it tomorrow.

A．was writing

B．will be writing

C．have written

D．have been writing

If x is a positive number and 1/2 the square root of x is the cube root of x, then x=（）.

A. 64

B. 32

C. 16

D. 4

E. 1