国家机关和有关单位不依法履行禁毒工作职责的，由同级禁毒委员会或者上级机关、主管部门责

Every generation has its emblematic boy’s toy. once upon a time there was the golf cart: a little toy car specifically designed for middle-aged men too rich to care about looking ridiculous. Later came the beach buggy, a briefly fashionable, wildly impractical, single-terrain vehicle. one might include the motorcycle or the snowmobile on this list, were they not, in certain contexts, quite useful, but there is no doubt which pointless recreational vehicle has captured the imagination of the landed, middle-aged celebrity: it’s the quad bike.

What is it about this squat, ungainly, easy-to-flip machine that celebrities love so much As recreational vehicles go, the quad bike is hardly sophisticated. They are to the countryside what the jet-ski is to Lake Windermere. "There’s nothing cool about a quad," says Simon Tiffin, editor of a well-known magazine. "It’s a strange thing to want to hare round beautiful bits of the country in a petrol-guzzling machine."

But celebrities love quad bikes. Musicians, comedians, DJs, actors and sportsmen have all been photographed aboard quads. "They’re the latest rich person’s toy," says Tiffin. "Spoilt children get them for Christmas." Provided you’ve got a large estate to go with it, however, the quad bike can remain a secret indulgence. You can go out and tear up your own piece of countryside without anyone knowing you’re doing it.

The quad bike’s nonsensical name -- "quad" means four, but "bike" is an abbreviation of "bicycle," which means two -- that comes to six -- hints at its odd history. Originally the ATV, or all-terrain vehicle, as quads are sometimes known, was developed in Japan as a three-wheeled farm vehicle, an inexpensive mini-tractor that could go just about anywhere. In the 1980s the more stable four-wheeled quad was officially introduced -- enthusiasts had been converting their trikes for some time -- again primarily for farming, but its recreational appeal soon became apparent. At the same time a market for racing models was developing.

Paul Anderson, a former British quad racing champion, says the quad’s recreational appeal lies in its potential to deliver a safe thrill. "It’s a mix between a motorbike and driving a car; when you turn a corner, you’ve got to lean into the corner, and then if the ground’s greasy, the rear end slides out," he says. "Plus they’re much easier to ride than a two-wheeled motorcycle." The quad bike, in short, provides middle-aged excitement for men who think a Harley might be a bit dangerous. Anderson is keen to point out that quad bikes are, in his experience, much safer than motorcycles. "With quad racing it’s very rare that we see anybody having an accident and getting injured," he says. "In the right hands, personally, I think a quad bike is a very safe recreational vehicle," he adds.

Outside of racing, quad bikes are growing in popularity and injuries have trebled in the last five years. Although retailers offer would-be purchasers basic safety instructions and recommend that riders wear gloves, helmets, goggles, boots and elbow pads, there is no licence required to drive a quad bike and few ways to encourage people to ride them wisely. Employers are required to provide training to workers who use quad bikes, but there is nothing to stop other buyers hurting themselves.

For the rest of the world, quad bikes are here to stay. They feature heavily in the programmes of holiday activity centres, they have all but replaced the tractor as the all-purpose, agricultural workhorse and now police constables ride them while patrolling the Merseyside coastline.

It has more or less usurped the beach buggy, the dirt bike and the snowmobile, anywhere they can go the quad bike can. They even race them on ice. You can’t drive round Lake Windermere on one, or at least nobody’s tried it yet. Just wait.

Which of the following statements is NOT true about quad bikes？（）

A．They can be ridden even on ice.

B．They can be used a great deal on farms.

C．They are driven by the police.

D．They are replaced by horses.

什么是橡胶加工的配料工序？

在荧光眼底血管造影检查中，有关透见荧光的描述，错误的是（）

A.可见于RPE萎缩

B.在荧光造影早期出现

C.造影晚期随着脉络膜染料的排空而减弱或消失

D.在造影晚期，其荧光变小

E.可见于先天性色素上皮减少

安全门防护罩的作用是保护操作人员的（）、降低噪音、美化外观。

黄釉绿彩