计算：$2\sqrt{12}\times \frac{\sqrt{3}}{4}÷\sqrt{2}$．

阅读短文，下列问题

B

    Not all inventions are made by scientists. Kids can also make history with their inventions.

    The state flagof Alaska was designed by 13-year-old Bennie Benson in 1926. His design was chosen from a flag-designing competition. It became the official flag in 1959. Bennie won a ＄1,000 scholarship（奖学金）and a watch.

    Frank Epperson invented the Popsicle in 1905 when he was only 11 years old. It was called the Epsicle at that time. Frank left his drink outside the door over night with a stick（木棒）in it. That night the temperature dropped and everything was frozen including Frank's drink. That didn't stop him from tasting it, so today we have Popsicles to eat.

    In 1642 Blaise Pascal designed the first counting machine when he was 18. The machine was forhis father, a tax collector, to make his job easier. Blaise named it “the Pasealine”. He made about 50 of them, but nobodywas interested in it. People thought it would take jobs away from them. 300 years went by, and the calculator（计算器）finally became a success. In 1968, the programming language（程序设计语言）, PASCAL, was named after him.

阅读短文，下列问题

B

    Not all inventions are made by scientists. Kids can also make history with their inventions.

    The state flagof Alaska was designed by 13-year-old Bennie Benson in 1926. His design was chosen from a flag-designing competition. It became the official flag in 1959. Bennie won a ＄1,000 scholarship（奖学金）and a watch.

    Frank Epperson invented the Popsicle in 1905 when he was only 11 years old. It was called the Epsicle at that time. Frank left his drink outside the door over night with a stick（木棒）in it. That night the temperature dropped and everything was frozen including Frank's drink. That didn't stop him from tasting it, so today we have Popsicles to eat.

    In 1642 Blaise Pascal designed the first counting machine when he was 18. The machine was forhis father, a tax collector, to make his job easier. Blaise named it “the Pasealine”. He made about 50 of them, but nobodywas interested in it. People thought it would take jobs away from them. 300 years went by, and the calculator（计算器）finally became a success. In 1968, the programming language（程序设计语言）, PASCAL, was named after him.

Some students spend ________ time on the Internet. They forget to study, eat and sleep. They can't even communicate with people in real life.

Some students spend ________ time on the Internet. They forget to study, eat and sleep. They can't even communicate with people in real life.

Some students spend ________ time on the Internet. They forget to study, eat and sleep. They can't even communicate with people in real life.

如图，在△ABC和△DCB中，∠A=∠D=90°，AC=BD，AC与BD相交于点O．

（1）求证：△ABO≌△DCO；

（2）△OBC是何种三角形？证明你的结论．

The maths problem is very easy, so I can work it out ________.

The maths problem is very easy, so I can work it out ________.

The maths problem is very easy, so I can work it out ________.