阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项。
A
When your pet has an emergency, first aid is not a substitute for veterinary(兽医的) treatment. However, before you are able to get your pet to a veterinarian, knowing some basic first aid can help.
Bite Wounds
Approach the pet carefully to avoid getting bitten. Wear a mask for the animal and then check the wound. Clean the wound with large amounts of saline (盐水). If these are not available, then regular water may be used. Wrap large open wounds to keep them clean.
Bleeding
Apply firm, direct pressure over the bleeding area until the bleeding stops. Hold the pressure for at least 10 minutes. Avoid bandages that cut off circulation.
Breathing Stops
Check to see if the animal is choking(窒息) on a foreign object. If an animal is not breathing, place it on a firm surface with its left side up. Check for a heartbeat. If you hear a heartbeat but not breathing, close the animal's mouth and breathe directly into its nose—not the mouth—until the chest expands. Repeat 12 to 15 times per minute.
Burns
Wash the burn immediately with large amounts of cool, running water. Apply an ice pack for 15－20 minutes. Do not place an ice pack directly on the skin. Wrap the pack in a light towel or other cover. If the animal has large quantities of dry chemicals on its skin, brush them off. Water may activate some dry chemicals.
Fractures (骨折)
Symptoms include pain, inability to use a limb(腿). Wear a mask for the pet and look for bleeding. If you can control bleeding without causing more injury，then do so. Watch for signs of shock. Don't try to set the fractures by pulling the limb. Transport the pet to the veterinarian immediately, supporting the injured part as best as you can.
语篇解读：本文是一篇说明文。文章主要介绍的是当宠物遇到紧急情况时，实施急救的几种办法。
21．The underlined word “substitute” in the first paragraph means something ．
A．that is necessary
B．that can replace other things
C．that is familiar with us
D．that can calm people
解析：选B 词义猜测题。根据下句However，before you are able to get your pet to a veterinarian, knowing some basic first aid can help.可知，急救虽然不能代替兽医的治疗，但在兽医到来前实施急救可以避免情况恶化。故选B。
22．If your pet is burned by chemicals, you should ．
A．wash away the chemicals with saline
B．put an ice pack directly on the skin
C．bind up the cut with a bandage
D．get rid of them before washing
解析：选D 细节理解题。根据Burns下的倒数第二句If the animal has large quantities of dry chemicals on its skin, brush them off.可知，如果宠物被化学药品烧伤，应该先把这些化学药品清除掉。故选D。
23．The passage is mainly about ．
A．doing pet first aid
B．treating sick pets
C．dealing with an emergency
D．working as a veterinarian
解析：选A 主旨大意题。文章介绍了当宠物遇到紧急情况时，人们应如何对其实施急救。故选A。
