The difference between an observational study and an experiment is that
in an observational study, only one group is studied, and in an experiment, two groups are studied.
in an observational study, the researchers do not control treatment, and in an experiment, they do.
in an experiment, cause-and-effect is analyzed, and in an observational study, it is not.
in an experiment, one group is studied over a short period of time, and in an observational study, the group is studied ove
a longer period of time.

b

Step-by-step explanation:

i just took the test

which would be true for stem changing verbs?

they have a consistent spelling change in the stem of the verb.

what is different about the verb “venir” as compared to other stem-changing verbs?

only the third person forms have a stem change.

which of the following could not be considered a “stem-changing” verb?

querer

which of the following would not be condsidered an event?

desfile

what word could be used in response to the following?

¿qué quieres comprar?

quero

what word could be used in response to the following?

¿dónde uds. pueden ir?

vamos  

ellos ir al centro comercial.

yo comprar un vestido.

pedimos

dónde tú?

dormes

step-by-step explanation: