语法填空 

A volcano is a place on the Earth's surface or any other planet's or moon's surface where molten rock, gases and pyroclastic debris erupt through the earth's crust.Volcanoes vary quite a (1)________ in their structure—some are cracks in the earth's crust (2)________ lava erupts, and some are domes, shields, or mountain?like structures with a crater at the summit.

Magma is molten rock within the Earth's crust.When magma erupts through the earth's surface (3)________ is called lava.Lava can be thick and slow?moving or thin (4)________ fast?moving.Rock also comes (5)________ volcanoes in other forms, (6)________ (include) ash and pumice.

The word volcano (7)________ (come) from the Roman god of fire, Vulcan.Vulcan was said to have had a forge  on Vulcano, (8)________ active volcano on the Lipari Islands in Italy.

The largest volcano on Earth is Hawaii's Mauna Loa.Mauna Loa is about 6 miles tall from the sea floor to its summit.It (9)________ has the greatest volume of any volcano, 10,200 cubic miles.The  (10)________ (active) volcano in the continental USA is Mt.St.Helens.

The largest volcano in our Solar System is perhaps Olympus Mons on the planet Mars.This enormous volcano is 17 miles tall and over 320 miles across.
二、本文主要描述了火山的形成和相关知识。

1．bit　quite a bit 相当于a lot。

2．where　先行词为the earth's crust，在从句中作地点状语，故填where。

3．it　主句中缺少主语，根据句意可知主语是magma，为避免重复，用代词it代替。

4．and　前文thick and slow?moving与thin and fast?moving为并列结构，故填并列连词and。

5．from　意思是Rock也来自于volcanoes。 

6．including　包括 ash and pumice在内，与主语存在逻辑上的主谓关系，故用其?ing形式。

7．comes　句中缺少谓语动词，且主语是The word volcano，单数名词，故填comes。

8．an　表示首次出现的某种事物，且后跟元音音素开头的词，故填an。

9．also　根据前文中的The largest volcano和后文的has the greatest volume可知填also表示“也”。

10．most active　根据文意此处应用形容词最高级。