下列现象中，由于光的直线传播而形成的是（　　）

    My dad works from Monday to Friday in a bank. He uses the computer to count money. His job is very important in the bank.

    Dad is also busy at home. At weekends he cooks dinner. Usually he cooks Italian food. On Sundays he makes five pieces of pizza. Sometimes he cooks chicken and makes Chinese food. My mum watches and helps him. I help my dad, too. I wash the dishes.

    Many people think it is strange for a man to cook. But my dad enjoys his hobby. Cooking relaxes him. He is a weekend cook.

I've asked him __________ us for dinner, but he said he was quite busy.