_________ dangerous to climb the mountain.

1. A.
   That's
2. B.
   It's
3. C.
   This is
4. D.
   Is

______ dangerous it is to ride fast on a busy road!

A．What    B．What a    C．How    D．How a

    dangerous it is to play soccer on a busy road!

A. How            B. What            C. What a

________dangerous it is to ride fast on a busy road!

A．What             B．What a           C．How               D．How a