Generally speaking, if ________ according to the instructions, the electric-bike is not so dangerous as reported．

1. A.
   riding
2. B.
   ridden
3. C.
   to ride
4. D.
   to be ridden

Generally speaking, ________according to the directions, the medicine has no side effect

1. A.
   when taken
2. B.
   when taking
3. C.
   when to take
4. D.
   when to be taken

Generally speaking, the publishers will send you a specimen copy of their new books when ________.

1. A.
   requested
2. B.
   requesting
3. C.
   having requested
4. D.
   to be requested

Generally speaking, the publishers will send you a specimen copy of their new books when ________.

A. requested    B. requesting     C. having requested  D. to be requested

Generally speaking , ______according to the directions , the drug has no side effect .

A．when taking    B．when taken      C．when to take    D．when to be taken