angular – Parser Error：得到插值({{}}),其中表达式是预期的

我的HTML如下：

<ul class="list-inline">
    <li class="tag" ngb-dropdown auto-close="outsideClick" 
        *ngFor="let item of ['Elastic Search','Database Theory','CVS'];
        let $index=index;" 
        [ngClass]="{'default-tag': $index==0,'matched-tag': $index==1,'unmatched-tag': $index==2 }">
         <a href ngb-dropdown-toggle id="desiredSkill{{$index}}">
             <i class="bi_interface-tick following"></i> {{item}} <i class="bi_interface-more tag-menu-icon"></i>
                            </a>
               <ul class="dropdown-menu tag-menu" ngb-dropdown-menu [aria-labelledby]="desiredSkill{{$index}}">
                     <li><a href>Follow Skill</a></li>
                     <li><a href>Related Jobs</a></li>
                </ul>
     </li>
  </ul>

但是当我运行我的应用程序时,我得到以下错误：

main.browser.ts:25Error: Template parse errors:
Parser Error: Got interpolation ({{}}) where expression was expected at column 12 in [desiredSkill{{$index}}] in
JobDescription@174:77 (”
][aria-labelledby]=”desiredSkill{{$index}}”>

“): JobDescription@174:77
Parser Error: Unexpected token ‘{‘ at column 13 in [desiredSkill{{$index}}] in JobDescription@174:77 (“

][aria-labelledby]=”desiredSkill{{$index}}”>

“): JobDescription@174:77
Can’t bind to ‘aria-labelledby’ since it isn’t a known property of ‘ul’. (”
][aria-labelledby]=”desiredSkill{{$index}}”>

“): JobDescription@174:77
Parser Error: Got interpolation ({{}}) where expression was expected at column 12 in [desiredSkill{{$index}}] in
JobDescription@174:77 (”

06001

JobDescription@215:49
Parser Error: Unexpected token ‘{‘ at column 13 in [desiredSkill{{$index}}] in JobDescription@174:77 (“

06001

JobDescription@215:49
Parser Error: Got interpolation ({{}}) where expression was expected at column 12 in [desiredSkill{{$index}}] in
JobDescription@174:77 (”
ERROR ->=”main.applyJob()”>Apply for job

ERROR ->=”main.applyJob()”>Apply for job

][hidden]=”!ifNotApplied”>Applied

][hidden]=”!ifNotApplied”>Applied

][hidden]=”!ifNotUploaded”>Upload CV

][hidden]=”!ifNotUploaded”>Upload CV

Have questions about this job?

[ERROR ->]

Have questions about this job?
[ERROR ->]