Which two sentences are written correctly?
astronauts aboard the international space station regularly conducts plant growth experiments in space.
the remaining leaves and the core of the lettuce plant are left intact and will continue to grow and produce more leaves.
the team of astronauts are working to supply the space station with fresh, nutritious food while in space.
"cut-and-come-again" is a repeated harvest technique in which only some of the leaves are harvested for a bit of fresh lettuce and for science samples.
one of the goals of the astronaut's experiments are to increase the yield of the lettuce plants.

The correct answers are B. The remaining leaves and the core of the lettuce plant are left intact and will continue to grow and produce more leaves and D. "Cut-and-come-again" is a repeated harvest technique in which only some of the leaves are harvested for a bit of fresh lettuce and for science samples.

Explanation:

One of the factors that make sentences correct is the agreement between subject and verb; in this way, it is expected a singular subject has a singular verb form and plural noun is followed by a plural verb.

This important grammatical rule is followed only in "the remaining leaves and the core of the lettuce plant are left..." because in this case both the subject and verb are plural, and in "Cut-and-come-again" is a repeated harvest technique..." because the subject "Cut-and-come-again" and the verb "is" are both singular. Therefore, only these two sentences are completely correct.

in a place once known as north america, now known as panem, is a very rich city surrounded by twelve districts. every year because this very rich city, known as the capitol, is so rich and likes to think they control all the districts - which they do - there is something known as the hunger games! this is where two children, one boy and one girl from each district from the ages of twelve to eighteen, have to leave their families and compete in the hunger games, a live event that is aired on tv's all over panem. when katniss everdeen, aged sixteen from district 12, has to volunteer to take the place of her twelve-year-old sister prim after prim's name is called forth to become the 23rd member to compete in the 74th hunger games, she promises to prim that she will win! katniss doesn't believe she's coming out alive - but she's not going down without a fight.

because district 12 is so poor, katniss has been close to death many times from starvation but she's made it through it. but this is a different kind of close to death; this katniss doesn't know if she can survive.

she doesn't want to hurt, or kill anyone but when it comes down to it katniss' instinct is to survive. but when she starts to have confusing feelings about the boy from her district who is also her fellow contender, things get worse, and then she teams up with the girl from district 11 and only one person can survive. but who will it be? will her feelings get the better of her? will she let someone else win so they don't have to die? if katniss is going to win she's going to have to be brutal. she's going to have to kill!