[填空题]
This image shows an aphid with its styletehi1-su.9b; oyjj)i n inserted into a plant. Aphi) zyvk/+ r0o9lkh n(:irtu 4v8cotx, yds have been used lk+cy t /:v rno( y4v)o90ztru xh8ki,to study transport in plants.
1.Name the tissue that aphids insert their stylets into.
This tissue is .
2.Outline how scientists use aphids to study the substance transported in this tissue.
3.Explain the differences in the contents and rate of flow of phloem sap at sources and sinks.
