Which sentence avoids an incorrect shift in verb voice?

when jamie switched on her laptop, she heard a piercing sound.
when bella opened her bedroom window, a cold wind was felt.
when jackson bit into the hardened candy apple, a tooth was lost.
when felipe traveled across the world, many cuisines were tried.

right angles are formed by perpendicular lines. if the lines would extend, to make two intersecting lines, they would form four right angles.

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.