用on the abacus造句子，“on the abacus”造句

As the students learn to manipulate the beads on the abacus, they learn to add and subtract.

She knew how to work on the abacus.

Starting this year, there will be a separate advanced class for the students who wish to continue and perform harder abacus and mental math problems as well as learn division on the abacus.

These industrial knights and princes might not be able to fence and ride like the knights and princes of the olden days, but they could do wonderful calculations on the abacus and drive motorcars.