Another oldie but goodie. You can select text in your Word document by using a couple of quick shortcuts. All of these are done in the left margin of your document. If you single click beside any line you select that line. If you double click beside a paragraph you select that paragraph. If you triple click anywhere in the margin you select the entire document.
In addition if you hold down the ALT (CMD on Mac) and click inside a sentence you will select that sentence.