ADT requires 'org.eclipse.wst.sse.core 0.0.0' but it could not be found ?

I faced the problem of ADT Plugin,I Cannot complete the install because one or more required items could not be found.

Software being installed: Android Development Tools 0.9.9.v201009221407-60953 (com.android.ide.eclipse.adt.feature.group 0.9.9.v201009221407-60953)
Missing requirement: Android Development Tools 0.9.9.v201009221407-60953 (com.android.ide.eclipse.adt.feature.group 0.9.9.v201009221407-60953) requires 'org.eclipse.wst.sse.core 0.0.0' but it could not be found

During installation, there's an error about requiring org.eclipse.wst.sse.ui. How do I fix that?

The Google Plugin for Eclipse depends on other specific Eclipse components, such as WST. Your installation of Eclipse may not yet include all of them, but they can be easily installed by following these instructions. Eclipse 3.6 (Helios)

1. Select Help > Install New Software...

2. Click the link for Available Software Sites.

3. Ensure there is an update site named Helios. If this is not present, click Add... and enter http://download.eclipse.org/releases/helios for the Location.

4. Now go through the installation steps; Eclipse should download and install the plugin's dependencies.

(There are examples in that page for 3.5 (Galileo), 3.4 (Ganymede) & 3.3 (Europa) for anyone with different versions)

The exact same steps work for 3.7 (Indigo) as well.

Just use http://download.eclipse.org/releases/indigo for the location.

Note: Step four is not necessary. Only steps one to three are necessary.