问题 单项选择题

某计算机字长为8位,它用补码、原码或反码来表示带符号的二进制整数(最高一位为符号位),则机器代码11111111所表示的十进制真值分别为 (4) (5) (6)

A.128

B.0

C.127

D.-0

答案

参考答案:D

解析:

[分析]: 机器代码11111111 用补码表示带符号的二进制整数时,其真值为10000001,即-1。答案D。
用原码表示时,对应的十进制真值为-(26+25+23+22+21+20)=127。答案D。
用反码表示时,其真值为10000000,对应的十进制真值为-0。答案D。

阅读理解

阅读理解。

     A teenager from Thousand Oaks received a warm welcome as he sailed into Marina del Rey on July 16,

2009, becoming the youngest person to circle the globe by sea alone.

     Zac Sunderland arrived in Marina Del Rey with his 36-foot boat Intrepid at about 10 am local time. During

his 28,000-nautical-mile journey, he braved storms, equipment failures and a conflict with suspected pirates

(海盗).

     "It's great to be back." Sunderland, of Thousand Oaks, California, said after he was welcomed home by

a group of friends.

     Fewer than 250 people have sailed around the globe alone, according to the American Sailing Association,

which certified (证实) Sunderland's feat.

     He left Marina del Rey, just south of Los Angeles, on June 14, 2008, and celebrated his 17th birthday at

sea while off Africa's Cape of Good Hope.

     His return was delayed near the end of his voyage when his boat had a broken bulkhead (舱壁) in rough

seas off Mexico, forcing him to stop at Puerto Vallarta long enough to wait for his father to fly there to make

repairs.

     Another tense moment occurred in the Indian Ocean off Indonesia where the Intrepid was approached by

a suspected a pirated boat.

     The intruders fled after a plane flew overhead and Sunderland climbed onto his deck with a gun to keep

them off, said Charlie Nobles, executive director of the association.

     Sunderland, who remained in contact with his father by satellite telephone during the voyage, threw the

gun away before entering Mexican waters, where it is illegal to carry private firearms.

     He becomes the first person under 18 to travel around the globe by sea alone, and the youngest to date.

The previous record-holder was David Dicks of Australia, who completed his voyage in November 1996 at

the age of 18.

1. Which statement about Sunderland's voyage is TRUE?

A. He completed his voyage in about 13 months.

B. He is the first one to travel around the globe by sea.

C. His father flew a plane to drive the pirates off.

D. On June 14, 2008, he reached the Cape of Good Hope.

2. Why did Sunderland stop at Puerto Vallarta?

A. To avoid the terrible weather.

B. To delay the time of his return.

C. To wait for help from his father.

D. To avoid the intruders.

3. What is the best title of the text?

A. A Brave Young Man

B. The Hardship Sunderland Experienced

C. Who Have Sailed Around the Globe Alone?

D. The Youngest Person to Circle the Globe Alone

单项选择题 A1/A2型题