present perfect: grammer

The number of people using mobile phones has .................... (rise) by 500 percent since 2003.

The invention of electronic books ...................(change) the way many people read.

Since I started using email, I.........................(not write) a traditional letter.

I ......................(forget) the word which means 'in the middle of the night'.

The library ............... (become) much more comfortable since they installed air conditioning.

It is a device to help people find keys which they

.................. (lose).