1 . But how do our phones know where in the world we are and in which direction we are going? It is all thanks to the satellites in space that help our phones ________ our position. ________ where you are around the world, your phone may be receiving data from different systems.（根据句意填空）

2 . Standing on the top of the hill, I would not do anything but ______ the flowing of the clouds around me.

A．to enjoy

B．enjoying

C．enjoyed

D．enjoy

3 . The jokes told by Tom made us ________, so the teacher couldn’t make himself ________.

A．to laugh; hearing

B．laugh; heard

C．laughing; hear

D．laughed; heard