题干

禽流感是由禽类流感病毒引起的,对家禽和人类有很大危害的传染病,下列叙述中属于体液免疫的是:①注射禽流感病毒疫苗,使机体产生抗体,与入侵的禽流感病毒结合,抑制病毒的活性 ②在人体内使禽流感失去感染人体细胞的能力 ③T细胞增殖分化形成效应T细胞 ④形成沉淀被吞噬细胞消化 ⑤效应T细胞与靶细胞密切接触,导致靶细胞裂解,释放出禽流感病毒 ⑥将患病的家禽深埋                     (     )

A:①②③

B:②⑤⑥

C:①③④

D:①②④

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D

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    Camels are large animals living in dry areas. There are two species of camels; the Arabian camel with a single hump(驼背) from the dry desert areas of West Asia, and the Bactrian camel with two humps from Central and East Asia. Camels are over 7 feet tall and weigh over 1,600 pounds. They will live up to 40 to 50 years. Most camels are domesticated(驯化) and fed by people. Camels are plant-eaters.

    Camels are very strong animals with wide, padded feet. They have thick leathery pads on their knees and chest. Camels have nostrils(鼻孔)that can open and close, protecting them from the desert environment. Bushy eyebrows and two rows of long eyelashes protect their eyes from sand. Their mouth is extremely tough, allowing camels to eat thorny(带刺的)desert plants. Their widened feet help them move without sinking into the sand. Their thick coats reflect sunlight, and also protect them from the intense heat from desert sand. Their long legs help by keeping them further from the hot ground.

    Camels can go without food and water for 3 to 4 days. They do not store water in their humps as is commonly believed.The humps are actually a container of fat. Camels are incredibly well-adapted to their environment. When conditions heat up, camels can increase their own body temperature, which prevents sweating and therefore water loss. They may not sweat at all during the day.

    Camels are sometimes called“ships of the desert”because people ride them around the hot, dry deserts of the world.However, the number of camels is becoming smaller for various reasons.