public interface IComputer    {        Task Do();    Task<string> DoString();}

public class Computer : IComputer    {        public Task Do()        {          return Task.Run(() => {            //邏輯代碼         });    }    public Task<string> DoString()            {                return Task.Run( () => {        //邏輯代碼 return "aaa";        });     }}

public Task Do()        {                    //邏輯代碼        return Task.CompletedTask;    }

/// <summary>Gets a task that has already completed successfully.</summary>/// <returns>The successfully completed task.</returns>public static Task CompletedTask { get; }

public Task<string> DoString() {    //邏輯代碼    return Task.FromResult("aaa");}

/// <summary>Creates a <see cref="T:System.Threading.Tasks.Task`1" /> that's completed successfully with the specified result.</summary>/// <param name="result">The result to store into the completed task.</param>/// <typeparam name="TResult">The type of the result returned by the task.</typeparam>/// <returns>The successfully completed task.</returns>public static Task<TResult> FromResult<[Nullable(2)] TResult>(TResult result);