angularjs2中导入其他模块的对象（该对象内嵌套另一个对象）并使用，编译时控制台提示该对象中不包含所嵌套的对象所以编译不通过，但是如果将另一个模块中的对象声明直接复制到同一个文件下，就一切正常。

控制台提示的错误如下：

问题代码如下：

//exercise-detail.component.ts
import { Component } from '@angular/core';

import { Exercise } from './exercise';


let exercise: Exercise = {
    id: 1,
    name: 'bench press',
    exerciseSets: [{
        id: 1,
        num: 1,
        previousWeight: 0,
        weight: 10,
        reps: 12,
        isFinish: true
    },{
        id: 2,
        num: 2,
        previousWeight: 0,
        weight: 10,
        reps: 12,
        isFinish: false
    }]
};

@Component({
    selector: 'exercise-detail',
    template: `
       <table border='1'>
           <tr>
               <td>finish?</td>
               <td>{{exercise.exerciseSets[1].isFinish}}</td>
           </tr>
       </table>
    `
})
export class ExerciseDetailComponent {

    exercise = exercise;
}
    

//exercise.ts
export class ExerciseSet {
    id: number;
    num: number;
    previousWeight: number;
    weight: number;
    reps: number;
    isFinish: boolean;
}

export class Exercise {

    id: number;
    name: string;
    exerciseSets: ExerciseSet[];
}

当将两个文件中的代码合并到一个文件后，就可以通过编译，输出正确。
合并后代码如下：

//exercise-detail.component.ts
import { Component } from '@angular/core';

export class ExerciseSet {
    id: number;
    num: number;
    previousWeight: number;
    weight: number;
    reps: number;
    isFinish: boolean;
}

export class Exercise {

    id: number;
    name: string;
    exerciseSets: ExerciseSet[];
}

let exercise: Exercise = {
    id: 1,
    name: 'bench press',
    exerciseSets: [{
        id: 1,
        num: 1,
        previousWeight: 0,
        weight: 10,
        reps: 12,
        isFinish: true
    },{
        id: 2,
        num: 2,
        previousWeight: 0,
        weight: 10,
        reps: 12,
        isFinish: false
    }]
};

@Component({
    selector: 'exercise-detail',
    template: `
       <table border='1'>
           <tr>
               <td>finish?</td>
               <td>{{exercise.exerciseSets[1].isFinish}}</td>
           </tr>
       </table>
    `
})
export class ExerciseDetailComponent {

    exercise = exercise;
}

我相信这问题很容易解决，并不是语法错误和逻辑错误，应该是Typescript对导入文件有要求，我刚用Typescript没多久，对它还不熟悉，望指教。