问题 单项选择题

在半闭环位置控制系统中,从位置编码器或旋转变压器等位置测量器件返回到数控系统中的轴运动位置信号仅仅反映了丝杠的转动位置,而丝杠本身的螺距误差和反向间隙必然会影响工作台的(),所以对丝杠的螺距误差进行正确的补偿在半闭环系统中是十分重要的。

A.与主轴中心线的垂直度

B.与主轴导轨的垂直度

C.定位精度

D.以上均错

答案

参考答案:C

单项选择题

(C)

Ocean Park Hong Kong is a theme park in the Southern District of Hong Kong Island. The park was built with donations from the Royal Hong Kong Jockey Club (now Hong Kong Jockey Club) and opened on 10 January 1977. The park is operated by Ocean Park Corporation, which is a statutory department. It offers affordable marine animal education and entertainment and is a private organization for commercial purposes.

In the early operation of the park, the main sources of income for the park were the ticket prices and the funding from the Jockey Club. Since the ticket price was low, most of the time Ocean Park was operating under deficit. In 1 July 1987, the government established a 200 million trust from the funding of Jockey Club, under the Ocean Park Corporation Ordinance. This separated Ocean Park from Jockey Club and became a non-profit organization; it needs to be responsible for its own income and was allowed to use commercial meansto operate the park.

Since it was permitted to use commercial means to operate, it gradually raised its ticket price and the deficit turned into profit. In 1992, 3 million visitors visited the park. Since 1998, the East Asian financial crisis, aging attractions, and the passing away of the killer whale; the park recorded a deficit for a couple years. Although it was allowed to host 2 pandas in 1999, the number of visitors did not go up and Ocean Park was forced to close its water attractions and the "Old Village" attraction and turned to bring in more rides in an attempt to capture the youth demand. Together with the opening up of mainland visitors under the Individual Visit Scheme, Ocean Park recorded an astonishing 4 million visitors in the year 2004-2005, the highest since the park opened.

In March 2005, Ocean Park made its redevelopment plan. On 23 November 2006, Ocean Park held a groundbreaking ceremony for its redevelopment.

Which of the following statements is Wrong()。

A. Ocean Park Hong Kong is a theme park.

B. Ocean Park Hong Kong has taken on a new look since 2005.

C. The East Asian financial crisis didn’t have any influence on Ocean Park.

D. At present, Ocean Park Hong Kong also attracts many mainland customers.

问答题 简答题