QUES: When piece measures 9910 1011 cm inc 1 st on each side of marker

correct the punctuation.

CORRECTED: When piece measures 9-9-10 (10-11) cm, inc 1 st on each side of marker.

QUES: At HRG we never stand still

correct the punctuation.

CORRECTED: At HRG we never stand still.

QUES: Then this is the Internet site you and your pupils have been looking for

correct the punctuation.

CORRECTED:
Then this is the Internet site you and your pupils have been looking for!