Replaced "can not" with "cannot" and "could not" in a bunch of places.
Fixed nearby grammar errors.
diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index 968056c..db47357 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -739,7 +739,7 @@
         ngx_temp_pool = ngx_create_pool(128, cycle->log);
         if (ngx_temp_pool == NULL) {
             ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
-                          "can not create ngx_temp_pool");
+                          "could not create ngx_temp_pool");
             exit(1);
         }
 
diff --git a/src/core/ngx_palloc.c b/src/core/ngx_palloc.c
index 35f1311..9eac114 100644
--- a/src/core/ngx_palloc.c
+++ b/src/core/ngx_palloc.c
@@ -68,7 +68,7 @@
 
     /*
      * we could allocate the pool->log from this pool
-     * so we can not use this log while the free()ing the pool
+     * so we cannot use this log while free()ing the pool
      */
 
     for (p = pool, n = pool->d.next; /* void */; p = n, n = n->d.next) {
diff --git a/src/core/ngx_string.c b/src/core/ngx_string.c
index 4dcfe01..75bc657 100644
--- a/src/core/ngx_string.c
+++ b/src/core/ngx_string.c
@@ -381,7 +381,7 @@
 
                     /*
                      * (int64_t) cast is required for msvc6:
-                     * it can not convert uint64_t to double
+                     * it cannot convert uint64_t to double
                      */
                     ui64 = (uint64_t) ((f - (int64_t) ui64) * scale + 0.5);