[intro.execution] p11 sequencing of co_await

[basic.exec.intro.execution] p11

For each function invocation or evaluation of an await-expression F, each evaluation that does not occur within F but is evaluated on the same thread and as part of the same signal handler (if any) is either sequenced before all evaluations that occur within F or sequenced after all evaluations that occur within F; if F invokes or resumes a coroutine ([expr.await]), only evaluations subsequent to the previous suspension (if any) and prior to the next suspension (if any) are considered to occur within F.

For invoking a coroutine(F is a coroutine call), the current wording seems to have no big problem. However, for co_await expression(IIUC, F refers to the co_await expression), It is a bit vague. I try to use the following illustration(not a c++ code) to expound on the problem I'm concerning. For concisely, ignore the suspension produced by initial-suspend and final suspend or they do not suspend a coroutine.

functionA(){
   // just talk about the suspension produced by user-written co_await expression
   // as per [expr.await], evaluate a single co_await consists of: 
   1: o expression
   2: r =  await-ready 
   3: r == false then suspension  // #1
   4: await-suspend 
        break point   // #2
   5: await-resume
}
int main(){
   functionA(); 
   // #3
   evaluation B
   resume functionA
   evaluation C
}

Firstly, I don't know why we need to say F resumes a coroutine. Consider line 1,2,3,4,5 is a complete evaluation of a single co_await expression(if ignore the suspension), when evaluating this co_await expression, if r is false, then at that point, the coroutine is considered suspension, assume await-suspend is a prvalue of type void, the control flow will back to #3, which means in this perspective, the evaluation 1, 2, 3, 4 should be considered to occur within F since evaluation B will be evaluated, which means line 5 is not considered occur within F at this point, otherwise evaluation B cannot be evaluated until at least line 5 has been evaluated. In this example, F does not resume any coroutine.

Moreover, consider at the beginning of evaluating the co_await expression, #1 is the next suspension, however, the line 4 still needs to be evaluated but it is after the "next suspension" point, in other words, the line 4 should be considered to occur within F. The above rule does not fit here.

When we back to #2 by "resume functionA", line 5 is considered to occur within F since it is subsequent to the previous suspension #1, which means "evaluation C" is either before or after the line 5.

Instead, in terms of the current wording, does it permit that the evaluation B could be sequence after 1, 2, 3? Since for function(coroutine) invoke F and co_await F', only 1, 2, 3 are considered to occur within F and F'.

Start with [basic.exec.intro.execution] paragraph 11 and the referenced [expr.await] rules. Trace the issue's numbered coroutine evaluations through suspension and resumption, then determine whether the sequencing wording is coherent for both invocation and co_await. Done means an agreed interpretation or revised standard wording that resolves the examples.