What is the meaning of "a speed greater than that of sound"?

What is the meaning of "to replace something or someone"?

What is the meaning of "put one image over another image so both are seen?"

Despite her busy work schedule, she still teaches and ____________________ her children’s schoolwork in the evening.

Kate hopes she can ____________________ her boss and take over his position in the company one day.

When the graphic artist makes the advertisement, he will ____________________ the company logo over the product’s image so both objects are visible.

I do not believe in the _______ such as ghost.

Garlic is a ____________ which fights high blood pressure, high cholesterol and many cancers.

The __________ paused to sign autographs for the crowd of fans waiting for him outside the restaurant.

___________ planes can travel faster than the speed of sound.

I got some pizzas at half-price at the _________.