问题 填空题

某二叉树中度为 2 的结点有 18 个,则该二叉树中有_________个叶子结点。

答案

参考答案:S

解析:二叉树的性质3:在任意一棵二叉树中,度为0的结点(即叶子结点)总是比度为2的结点多一个。本 题中度为2的结点数为18,故叶子结点数为18+1=19个。

阅读理解

阅读理解。

Garden Route, South Africa

     Take in fresh sea air in this beautiful coastal setting as you cruise the famous Garden Route

in the Western Cape in South Africa. A wildlife break is a must, as is enjoying great meal stops

along the route. There are wildlife reserves throughout the Graden Route National Park you can

swing into and spend a sleepy morning in a car looking for giraffes and lions. And just over your

shoulder in the big blue there are whales to be watched (if the season is right).

     Top tip: Add a trip to the Eastern Cape to your Garden Route trip. It is much less known than

the Western Cape and full of great landscapes. The gas station is occasionally seen.

Great Ocean Road, Australia

     Sweep along this dramatic coastal road in Austrlia with views of the Southern Ocean from

Geelong to Portland, in Victoria, and you won't regret it. Anyone who has driven it just can't stop

talking about it, and with good reason. There're loads to see and plenty of great stops. There's

whale-watching here too, and other natural life. And to top it all, there'll be plenty of good old

Aussie kindness and welcome when you pull in for lunch or a coffee stop.

     Top tip: Rent an open-top car so you can really drink in that sea air.

Stelvio Pass, Italy

     If you like snake-like paths and mountain passes, you'll love this. Stelvio in Italy. The mountain

slopes stretch away on either side of the road, with snow-topped peaks within sight. There's a great

view down the pass. And from the top, it's just a short sweep away from the Swiss border, so if you

are gripped by mountain road driving, you can drive from here down to Swiss ski resort of Davos.

Stelvio has 48 hairpins(急弯) on the north side and 12 on the descent(陡坡) to Bormio, so this route

is not recommended for new drivers, or those with a fear of heights. This descent is often featured in

the Giro d'Italia, the Italian version of the Tour de France, so you may have glimpsed it on the television.

     Top Tip: Take some Swiss Francs as well as some Euros, so you can make the trip a cross-border

experience.

1. In which travel routes can one enjoy whale watching?

A. Stelvio Pass, Italy and Garden Route, South Africa.

B. Great Ocean Road, Australia and Stelvio Pass, Italy.

C. Garden Route, South Africa and no other route.

D. Great Ocean Road, Australia and Garden Route, South Africa.

2. The tips in the ad are meant to             .

A. introduce a new route to the drivers

B. help drivers find gas stations on the route

C. give useful advice to make the trip more pleasant

D. warn drivers of the possible dangers on the road

3. Compared with the other two routes, Stelvio Pass is special in that          .

A. it's more winding and challenging

B. it's safe and more suitable for new drivers

C. it has lots of wild animals on either side of the road

D. it's often featured in Tour de France and thus more famous

4. What's the best title for the travel advertisement?

A. Drive to South Africa, Man!

B. Drive travel for Whale Watching!

C. A Travel to Three Continents!

D. Exciting Drive Travel in the Wild!

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