MANIFEST.FM找不到JARS

Question

我目前正在开发一个eclipse插件，所以我刚开始使用JDE。 我参考了我项目中所需的所有JAR，但我的MANIFEST.MF中仍然存在错误：

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Module-builder
Bundle-SymbolicName: module-builder;singleton:=true
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: module_builder.Activator
Require-Bundle: org.eclipse.ui,
 org.eclipse.core.runtime
Bundle-RequiredExecutionEnvironment: JavaSE-1.7
Bundle-ActivationPolicy: lazy

错误

org.eclipse.ui cannot be resolved
org.eclipse.core.runtime cannot be resolved

这些错误可能来自哪里？

编辑： 如上所述，.project内容：

 <?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
        <name>module-builder</name>
        <comment></comment>
        <projects>
        </projects>
        <buildSpec>
                <buildCommand>
                        <name>org.eclipse.jdt.core.javabuilder</name>
                        <arguments>
                        </arguments>
                </buildCommand>
                <buildCommand>
                        <name>org.eclipse.pde.ManifestBuilder</name>
                        <arguments>
                        </arguments>
                </buildCommand>
                <buildCommand>
                        <name>org.eclipse.pde.SchemaBuilder</name>
                        <arguments>
                        </arguments>
                </buildCommand>
        </buildSpec>
        <natures>
                <nature>org.eclipse.pde.PluginNature</nature>
                <nature>org.eclipse.jdt.core.javanature</nature>
        </natures>
</projectDescription>