"you'd better straighten up or you will be looking for someone else to date." i think you better straighten up or else you will be finding someone else to date. i think you better take this relationship seriously or you will be looking for a new date. i need for you to take our relationship seriously because i feel i am doing all the work.

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.

First to answer will be the brainliest i need the answer asap

What are the four types of infections?