Jim lived in a town near New York. His father had a shop there and his mother was a doctor. He was seven years old this year and began to go to school this September. It was a little far（远） from their shop and his father drove a car to take him to school five days a week. So he was never late for school and his teachers liked him very much. It was Monday that day. Miss White was teaching them to count from one to ten in the morning. Jim was studying hard. Soon he could count them. Miss White was happy and asked, “How many people are there in your family, Jim?” Jim stood up and said, “Two, Miss White.” “Who are they?” “My father and my mother.” “Oh?” Miss White was very surprised. She then said, “There are three people in your family.” “But now I’m not at home. I’m at school, you know!”

小题1:Where did Jim’s father work?

A．In a factory

B．In a school

C．In a shop

D．In a hospital小题2: Jim was a student of _______.

A．Grade One

B．Grade Two

C．Grade Three

D．Grade Four小题3:How many people are there in Jim’s family?

A．Two

B．Three

C．Four

D．One

不经计算，通过直接判定得知图示桁架中零杆的数目为：（）

A.1根

B.2根

C.3根

D.4根