B4

Do you like airplanes?

For people who have never flown in a plane before, the first flight can be an exciting and scary experience.

(present perfect, т.к. действие продолжается до настоящего момента)

NEVER FLY

B5

The secret is to sit back and enjoy it. Flying is incredibly safe these days.

(мн. число от this)

THIS

B6

In fact, it's one of the safest ways to travel.

(степень сравнения)

SAFE

B7

Sometimes during a flight the plane can move up and down, making  the plane shake a little.

(Participle I, “заставляя”, подходит по смысловому контексту)

MAKE

B8

Don’t worry if this happens.

(повелительное наклонение)

NOT WORRY

B9

If you are standing up talking to friends when it happens, sit down again.

(present continuous, т.к. глаголы должны согласовываться; standing и talking)

STAND

B10

Make sure your seatbelt is done up and wait for the movement to stop.

(твой)

YOU

B11

You might also sometimes hear strange noises on a plane but they're nothing to worry about either.

(звуки; обращайте внимание на последующие местоимения)

NOISE