Phrasal idioms with the verb 'drop'

Many parents assume that their children will ......... in school if they spend too much time playing video games.
drop off
drop out
drop over
drop behind

Children who ......... of school face a high risk of sexual exploitation, hazardous labor, and living in the street.
drop off
drop out
drop behind
drop in

It is not necessary to attend every class in order to participate, so please ......... and join the fun!
drop off
drop in on
drop behind
drop in

Students who are required to pass a test to enter the 9th grade are more likely to ......... prior to entering 10th grade.
drop off
drop out
drop behind
drop in

A 27-year-old Canadian woman confused the weekend with a weekday and ......... her 6-year-old at school on a Saturday.
dropped off
dropped out
dropped behind
dropped in

Visitors attending the annual Open House have the options of either participating in information sessions for their entire duration or ......... portions of the seminars based on their schedule and interest.
dropping out
dropping in
dropping behind
dropping in on

Special ramps for picking up and ......... passengers are provided at the curbs of the arrival and departure floors of each terminal.
dropping off
dropping out
dropping behind
dropping in

Unannounced visits are usual on campus, and guests are always welcome. Friends sometimes ......... one another, but it is mostly relatives who visit each other and mothers who frequently meet with their daughters.
drop off
drop in on
drop behind
drop in

Please ......... between 4:30 and 6:30 p.m. this coming Wednesday, November 16, for drinks, hors d'oeuvres, and conversation.
drop off
drop in on
drop in
drop behind

Senior Constable Smith asked the suspect to ......... the police station at lunch time in order to answer some questions regarding his alleged involvement in a bank robbery.
drop over
drop off
drop out
drop by