Here are some videos about service.
Doubleservice with 3. hit:
Student serves shor" with backhand. Coach returns "too high" over net (like bad return). Student should kill this return.
a) Direction of the short return is known by the student.
b) Direction of the short return varies.
c) The double partner is included. After a short serve, the server stays in front and the other player smashes.
Comments for this video:
The services are partly hitten from too deep.