Preposition: of

• moorland: Extensive tract of dry moorland, Mountain grass, moor bent grass.

• rainforest: The south is much wilder, with huge unbroken tracts of rainforest.

• heathland: The plan has been created with the aims of preventing further decline and restoring vast tracts of heathland back to their former glory.

• land: Never was a more barren tract of land than these seven or eight miles.

• wilderness: Yet 90 per cent of the population lives within 100 miles of the US border, leaving huge tracts of unspoiled wilderness elsewhere.

• farmland: Benetton owns vast tracts of farmland in southern Argentina, where it rears sheep to provide wool for its garments.

Converse of object

• irritate: These fumes may cause occupational asthma and can also irritate the upper respiratory tract and eyes.

• inhabit: Probiotics and Beneficial Bacteria Researchers estimate that more than 400 species of bacteria inhabit the digestive tract.

Adjective modifier

• gastrointestinal: It is only poorly absorbed from the gastrointestinal tract in the presence of intact mucosa.

• digestive: Ideally small children, who have got very short digestive tracts compared to adults, should go about twice a day.

• urinary: The most common part of the urinary tract to get infection is the bladder.

• respiratory: Slow virus infections of the respiratory tract of sheep.

• intestinal: Take care not to puncture any part of the intestinal tract.

• gastro-intestinal: We focus on tumors of the head and neck, breast, lower gastro-intestinal tract, prostate and basal cell carcinoma of the skin.

Modifies a noun

• infection: During the winter months respiratory tract infections with a variety of viruses are more common.

• obstruction: For example, urinary tract obstruction, can be treated to save renal function.

• symptom: One-fourth of these men will develop moderate to severe lower urinary tract symptoms that greatly affect their quality of life.

Noun used with modifier

• outflow: I'd known he had something but this is the first time the doctor called it the outflow tract obstruction.

• inlet: Fit the reed valve assembly into the inlet tract, taking care not to damage the petals.

• sinus: They sometimes rupture and discharge fluid or pus, and sometimes open sinus tracts form.