androidStudio出现R无法识别比对下面build.gradule

apply plugin: ‘com.android.application’

android {
compileSdkVersion 23
buildToolsVersion “23.0.3”

defaultConfig {    applicationId "tw.tweb.message.myapplication"    minSdkVersion 15    targetSdkVersion 23    versionCode 1    versionName "1.0"}buildTypes {    release {        minifyEnabled false        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'    }}

}

dependencies {
compile fileTree(dir: ‘libs’, include: [‘*.jar’])
testCompile ‘junit:junit:4.12’
compile ‘com.android.support:appcompat-v7:23.2.1’
}