Douglas腔

A . A、人每分钟都需要被注意 B . B、人是无能的，责任是虚无的 C . C、人尽可能的逃避工作 D . D、人可以指挥自身努力

A . $2，000有利 B . $5，000有利 C . $5，000不利 D . $2，000不利

A . 正确 B . 错误

A . 利福平 B . 异烟肼 C . 吡嗪酰胺 D . 异烟肼，利福平，卡那霉素，丁胺卡那霉素 E . 链霉素，对氨基水杨酸钠

A . 正确 B . 错误

A . GUI技术 B . 几何画板 C . 手写板 D . 鼠标

A . A、牵引电机 B . B、截割电机 C . C、液压管路、水管和电缆 D . D、各级齿轮传动组件和齿轮油

A . 1～2 B . 2～3 C . 3～4 D . 4～5

A . Dislikes work and avoids it whenever possible B . Must be closely supervised and even threatened with punishment C . Avoids increased responsibility D . Wants self-respect E . None of the above

A．whether video games can produce long-term impact on the youth. B．the effect of playing pro-social games on the youth. C．whether the youth are able to classify different video games. D．the effect of playing violent games on the youth"s moral fabric.

A．球囊充气腔 B．热敏电阻管腔 C．CVP D．PAP

A．Maybe some other time. B．Well, if you insist. C．Who cares？ D．I"d be glad to.

The puzzle had to do with waves. Though it might seem intuitive that waves carry water to shore, and sand along with it, it's not that simple. The crest(浪尖)of a passing wave lifts a given hit of water upward and landward, but the ensuing trough(波谷) pushes the water back down and Out to sea. Near the bottom, there the sand is, the water was always assumed to just slide back and forth—and the sand with it. "If you take a very aloof look at a beach," says Inman, "you'll realize that if the two motions move sand back and forth the same amount, then all the sand should end up in deep water.' So for beaches to exist, the crest's onshore flow must somehow move enough sand up the beach to counter the seaward tug of both the trough and gravity . The pressure changes in the sand bed, Inman and Conley think, are the key to beach creation. They found that sand doesn't just slide back and forth with each passing wave. Under a trough, it does slide seaward, in a thin layer just above the bottom. But under a crest its movement is often more elaborate. The higher pressure under a crest—higher because the water is piled higher—forces water into the porous(多孔的) sand. This creates strong whirlpools just above the sand, which help loosen it. As the crest passes overhead, the sand first rushes across the bottom; then it abruptly turns violent lifting off the bottom in large, boiling bunches. Finally, just after the crest passes, the sand explodes up into the great water column. The boiling and rushing move more sand than the backsliding under a trough, so there's a net movement of sand toward the shore. What is the primary purpose of this passage？ A．To explain why sand piles up on the beaches. B．To explain why men only prostrate in the sea. C．To propose a new explanation of a phenomenon. D．To refute a misconception.