But for friction (摩擦力), people ______ neither walk, nor even stand up.

A. can                                        B. were able to      C. will be able to                   D. could

Without the friction (摩擦力) between feet and the ground, people would ______ be able to walk.

A. in no time     B. by all means  C. on any account      D. in no way

But for friction (摩擦力), people ______ neither walk, nor even stand up.

1. A.
   can
2. B.
   were able to
3. C.
   will be able to
4. D.
   could

Without the friction  (摩擦力) between feet and the ground, people would ____ be able to walk. 
A. in no time     B. by all means     C. in no way     D. on any account