B1U10 Passive voice

Silicon _____ in sand.

• is found

• are found

The silicon _____ to be 100% pure.

• is refined

• are refined

The pure silicon _____ and _____ into small blocks called ingots.

• is heated/is made

• is heated/are made

• are heated/is made

• are heated/are made

The ingots _____ into very small pieces and then later become thin chips.

• is cut

• are cut

Tiny components _____ to the chips.

• is added

• are added

Eight hundred transistors _____ onto an area with the diameter of a human hair!

• is put

• are put

Special clothes and masks _____ by workers to protect the chips.

• is worn

• are worn

Finally, the chips _____ to computer factories.

• is sent

• are sent